Newses & Articles

Does Food Color Influence Taste and Flavor Perceptionin Humans?Charles Spence & Carmel A. Levitan &Maya U. Shankar & Massimiliano Zampini

Publish Date : 1395/6/6 Time 12:41:03

distinguish between the evidence pertinent to evaluating

two relatively independent research questions: (1) Does the

presence versus absence, or change in the intensity, of

the color present in a food or drink influence people’s

perception of the intensity of a particular flavor (e.g.,

banana, strawberry, etc.) or taste (such as sweetness,

sourness, etc.)? (2) Does food coloring influence the correct

identification of a food or drink’s flavor?

The evidence concerning the first question is indeed

rather mixed (Auvray and Spence 2008; Stevenson 2009;

Zampini et al. 2007), with some researchers observing a

significant effect of changing the intensity of the coloring

added to a food on people’s judgments of flavor and/or taste

intensity (e.g., Johnson and Clydesdale 1982; Johnson et al.

1982, 1983;Rothetal.1988), while many others have failed

to demonstrate any such effect (e.g., Alley and Alley 1998;

Frank et al. 1989;seeTable1). By contrast, the published

evidence unequivocally supports an affirmative answer to the

second question, with people’s judgments of a flavor’s

identity often being reliably affected by a food’scolor,beit

appropriate, inappropriate, or absent. Note here that we are

not aware of any research having been conducted assessing

the effect of color on the identification of basic tastes (e.g.,

when solutions containing an odorless tastant such as sugar

or salt are sampled). Below, we review the evidence relating

to these two questions. We discuss several of the possible

mechanisms that may underlie these crossmodal effects on

taste and flavor identification, such as cognitive expectancy,

bottom-up multisensory integration, and attention.

Which Senses Contribute to the Perception of Flavor?

Before we proceed, however, it is important to note that

gustatory, olfactory, and oral–somatosensory cues (in

contrast to visual and auditory cues) all contribute directly

to flavor perception. In fact, the International Standards

Organization (ISO 5492 1992) has defined flavor as a

“complex combination of the olfa ctory, gustatory and

trigeminal sensations perceived during tasting. The flavor

may be influenced by tactile, thermal, painful and/or

kinaesthetic effects” (see Delwiche 2004, p. 137; see also

ISO 5492 2008). Visual and auditory cues may modify a

food’s flavor, but they are not, at least according to the ISO

definition, intrinsic to it (though see also Auvray and

Spence 2008; Stevens on 2009 for alternative views). Visual

cues, such as a f ood’s color, may then modify the

perception of a food’s flavor by influencing the gustatory

qualities of the food, by influencing the olfac tory attributes

of the food (as perceived orthonasally and/or retronasally;

Koza et al. 2005), by influencing the oral–somatosensory

qualities of the food, and/or by influencing the overall

multisensory flavor percept (or Gestalt; see Fig. 1). In this

article, we review the evidence regarding color’s effect on

taste and flavor. We also discuss the evidence regarding

color’s influence on olfactory judgments where relevant.

1

Does Food Color Influe nce Perceived Taste or Flavor

Intensity?

The evidence pertaining to the question of whether food

coloring influences people’s perception (or ratings) of taste

or flavor intensity is currently rathe r ambiguous: that is,

while a number of studies have demonstrated a significant

effect of increasing the level of food coloring on people’s

ratings of taste or flavor intensity across a range of different

drinks (Hyman 1983; Johnson and Clydesdale 1982;

Johnson et al. 1982, 1983; Kostyla 1978; Romeu and De

Vicente 1968; Roth e t al. 1988), many other studies have

either failed to demonstrate any such crossmodal effect (e.g.,

Alley and Alley 1998; Chan and Kane-Martinelli 1997;

Frank et al. 1989; Gifford and Clydesdale 1986; Gifford et

al. 1987), or else have demonstrated complex (and/or

unexpected) interactions that have proved rather more

difficult to interpret (e.g., Christensen 1985; DuBose et al.

1980, experiment 1; Fletcher et al. 1991; Lavin and

Lawless 1998; McCullough et al. 1978 ; Pangborn 1960;

Strugnell 1997; Zampini et al. 2007; experiment 2).

2

Given

that the evidence regarding color’s influence on taste

intensity would appear to be rather more ambiguous than

its effect on flavor intensity, the evidence pertaining to each

of these is dealt with separately in the following sections.

Does food color influence taste intensity? One of the

classic studies to investigate color’s influence on taste

sensitivity was conducted by Maga (1974). He investigated

the effects of coloring an aqueous solution red, green, or

1

It should be noted that the near absence of research means that, as

yet, there is nothing much to say about vision’s influence, if any, on

the oral–somatosensory attributes of flavor (see Christensen 1983;de

Wijk et al. 2004; Frost and Janhoj 2007 for exceptions; see Verhagen

and Engelen 2006 for a review).

2

Over the years, researchers have looked at color’s role in influencing

people’s perception of the taste and flavor of many different foods,

including jellies (Moir 1936), cake (DuBose et al. 1980; Moir 1936;

Tom et al. 1987), chocolate (Duncker 1939; Levitan et al. 2008;

Shankar et al. 2009), syrups (Kanig 1955), sherbets (Hall 1958), wine

gums (Tee rling 1992), and yogurt (Norton and Johnson 1987).

However, more recently, the majority of the research has tended to

use various different drinks, beverages, and solutions as the stimuli of

choice. Most likely, this research focus on colored drinks (be they

carbonated or uncarbonated) reflects both the ease of stimulus control

and creation that such experimental materials afford and also the fact

that color provides one of the few distinctive non-olfactory features of

such stimuli (see Christensen 1985; Oram et al. 1995). Given this bias

in the literature, we have also chosen to focus our review primarily on

those studies that have investigated the effect of color on taste and

flavor perception in various solutions, drinks, and beverages.

Chem. Percept. (2010) 3:68–84 69

yellow on perceptual thresholds for four of the basic tastes

(salty, sour, sweet, and bitter). Note that each of the basic

tastes was tested in a separate part of the experiment,

meaning that the participants were presumably never

uncertain with regard to the identity of the tastant whose

presence they were trying to detect. In many cases, Maga

observed that the concentration of the tastant had to be

increased in order for his participants to be able to detect its

presence in the colored (as compared to the uncolored)

solutions. So, for example, the addition of green coloring

to a sweet solution significantly increased taste sensitivity,

while yellow color decreased taste sensitivity (see Table 2).

Interestingly, red coloring had no significant effect on

sensitivity to sweet taste. With respect to sour taste

sensitivity, both the yellow and green coloring of solutions

decreased participants’ sensitivity, with red coloring again

having no effect. Coloring a clear solution red decreased

bitter taste sensitivity, while the addition of yellow and green

coloring had no such effect. Finally, adding color had no

effect on taste detection thresholds for salt solutions.

Johnson and Clydesdale (1982), in an oft-cited study,

demonstrated an effect of food coloring on taste perception

in sweetened solutions (that sometimes contai ned a cherry

flavoring). The participants in their study had to perform

both a threshold task and a magnitude estimation task. In

the threshold task, Johnson and Clydesdale found that on

average, when odorless solutions were colored red, partic-

ipants could more easily detect the presence of sucrose than

when they were uncolo red (cf. Maga 1974), though the

intensity of the color did not have a significant effect on

their performance. In the magnitude estimation task,

however, Johnson and Clydesdale found that changing the

level of food coloring had a significant effect on partic-

ipants’ perception of the sweetness of both odorless and

cherry-flavored solutions, with the darker-colored solutions

being rated as 2–10% sweeter than the lighter-colored

Table 1 Summary of the studies that have been published to date that have investigated the effect of varying the presence vs. absence, the

appropriateness/inappropriateness, or the intensity, of the color added to a solution on participants’ taste and/or flavor (Fl) intensity ratings. The table

highlights the fact that the majority of research in this area has focused on the influence of color on sweetness perception. The table also highlights the

inconsistency in the pattern of results that has been reported to date across the various studies that have been reported

Study Tastant Flavor Result

Pangborn (1960) Sw, So Sig

Pangborn et al. (1963) Sw Sig

Romeu and De Vicente (1968) Fl Sig

Maga (1974) Sw, Sa, So, Bi Sig

Kostyla (1978 ) Sw, So Fl Sig

McCullough et al. (1978) Sw Complex

DuBose et al. (1980) Fl Complex

Johnson and Clydesdale (1982) Sw Sig

Johnson et al. (1982) Sw Sig

Hyman (1983) Fl Sig

Johnson et al. (1983) Sw Sig

Gifford and Clydesdale (1986) Sa n.s.

Gifford et al. (1987) Sa n.s.

Roth et al. (1988) Sw Sig

Frank et al. (1989) Sw n.s.

Fletcher et al. (1991) Sw Complex

Philipsen et al. (1995) Sw Sig

Chan and Kane-Martinelli (1997) Sa n.s.

Strugnell (1997) Sw Sig

Alley and Alley (1998) Sw n.s.

Lavin and Lawless (1998) Sw Complex

Bayarri et al. (2001) Sw Fl Complex

Zampini et al. (2007) Fl Complex

Zampini et al. (2008) Sw, So Fl Complex

Sw sweet, Sa salt, So sour, Sig significant result, n.s. non-significant result, Complex typically a mixture of significant and non-significant results

Table 1 Summary of the studies that have been published to date that

have investigated the effect of varying the presence vs. absence, the

appropriateness/inappropriateness, or the intensity, of the color added to

a solution on participants’ taste and/or flavor (Fl) intensity ratings. The

table highlights the fact that the majority of research in this area has

focused on the influence of color on sweetness perception. The table

also highlights the inconsistency in the pattern of results that has been

reported to date across the various studies that have been reported

70 Chem. Percept. (2010) 3:68–84

reference solutions despite the fact that the actual concen-

tration of sucrose was 1% lower. In further studies, Johnson

and his colleagues went on to use the same magnitude

estimation procedure in order to sho w that sweetness

ratings for both cherry- (Johnson et al. 1982)and

strawberry-flavored drinks (Johnson et al. 1983) increased

by 2–13% when the intensity of the cherry red coloring was

increased. Over the years, several further studies have also

documented a significant effect of the addition of (specifical-

ly) red food coloring on the perception of sweetness (e.g., see

Kostyla 1978; Pangborn 1960; Strugnell 1997).

Color cues have also been reported to influence parti-

cipants’ ratings of sourness/tartness (e.g., Kostyla 1978;

Pangborn 1960). By contrast, the null result of color on the

detection threshold for the presence of salt in aqueous solu-

tions reported by Maga (1974) has been extended in several

other well-controlled laboratory studies in which coloring

was added to more ecologically valid food substrates, such as

chicken broth (see Chan and Kane-Martinelli 1997;Gifford

and Clydesdale 1986; Gifford et al. 1987). In order to try and

explain this seemingly inconsistent effect of the addition of

color on salt and sweetness perception, Maga suggested that

color might not have any effect on salt perception because

salty foods can come in any color, and hence, people have few

direct color associations with saltiness.

Maga (1974) argued that there is a natural correlation

between redness and sweetness levels as many fruits ripen.

That is, many fruits show a transition from colors at the

green end of the spectrum, through yellow, to colors at the

red end of the spectrum (see also Brice 1954; Kostyla 1978;

Lavin and Lawless 1998; Zampini et al. 2007 on this point).

Maga suggested that prior exposure to this natural color–taste

correlation (i.e., between increases in redness and sweetness in

foods) might help explain why red/green coloring should have

such a profound effect on sweetness/sourness perception.

Consistent with this suggestion, Pangborn (1960)demon-

strated that the addition of green food coloring reduced

sweetness ratings while enhancing sourness ratings in pear

nectar, though it should be noted that Pangborn and Hansen

(1963) subsequently failed to replicate this finding. A

consistent pattern of results has been reported more recently

in a study by Lavin and Lawless (1998). The participants in

this study were given four strawberry-flavored drinks of

different colors (light and dark red and light and dark green)

to rate for sweetness using a nine-point categorical scale. The

participants rated the dark red solutions as sweeter than light

red solutions, but light green solutions as sweeter than dark

green solutions.

While the results discussed thus far in this section would

appear to demonstrate that the addition (vs. absence) of

food coloring leads to a significant effect on ratings of

the presence (vs. absence; Johnson and Clydesdale 1982;

Maga 1974) of sweetness and that increasing the intensity

Table 2 Summary of the re sults f rom Maga ’s(1974) study

highlighting the effect of the addition of color on participants’

sensitivity to each of the four traditional basic tastants when dissolved

in solution (and compared to performance when the tastants were

presented in uncolored solutions)

Color of

solution

Taste

Sour

(citric acid)

Sweet

(sucrose)

Salty (sodium

chloride)

Bitter

(caffeine)

Red No effect No effect No effect Decrease

Yellow Decrease Decrease No effect No effect

Green Decrease Increase No effect No effect

Vision

Flavour

Oral-

Somatosensation

Fig. 1 This figure highlights the multiple ways in which visual cues

might influence flavor perception. Visual cues (such as the color of a

beverage) may exert a crossmodal influence on olfaction, gustation,

and/or on oral somatosensation. Such crossmodal effects, should they

exist, might then have a carryover effect on the experienced flavor

percept once the various unisensory cues have been integra ted.

Alternatively, however, visual information might influence flavor

perception only once the olfactory, gustatory, and/or oral–somatosen-

sory cues have been integrated into a multisensory flavor percept (so,

for example, if you bite into a filled chocolate, then look to see what

color the filling of the chocolate has, then color may well influence the

integrated flavor percept). Complicating matters still further, the

nature of the crossmodal influence of visual cues on flavor perception

may well vary with the task at hand. That is, different results may be

observed as a function of whether participants are asked to report on

the pleasantness or intensity of a flavor versus having to identify or

discriminate the flavor. There is robust psychophysical evidence that

visual (color) cues can modulate people’s perception of the identity

and intensity of both orthonasally and retronasally presented odors

(e.g., Blackwell 1995; Davis 1981; Engen 1972; Morrot et al. 2001;

Zellner et al. 1991; Zellner and Kautz 1990; Zellner and Whitten

1999). There is also convincing psychophysical evidence that visual

(color) cues can influence people’s perception of the intensity of the

basic tastants when presented in odorless solutions (Johnson and

Clydesdale 1982; Maga 1974). Interestingly, however, we are aware of

no research that has directly addressed the question of whether color

cues can influence a participant’s ability to discriminate (and/or

identify) the identity of basic tastants when presented in solution. To

date, there is only very limited research detailing any visual

contributions to the oral–somatosensory attributes of food. Evidence

demonstrating the robust influence of visual cues on flavor identifi-

cation is discussed in the text, as is the rather more mixed evidence

concerning the influence of visual (color) cues on perceived taste and

flavor intensity

Chem. Percept. (2010) 3:68–84 71

of color can increase perceived sweetness intensity ratings

(Johnson and Clydesdale 1982 ; Johnson et al. 1982, 1983;

Roth et al. 1988), it is important to note that many other

studies have failed to demonstrate any such effect (see

Alley and Alley 1998; Christensen 1985; Frank et al. 1989;

McCullough et al. 1978;Pangborn1960; see also Johnson

and Cly desdale 1982). For example, Alley and Alley

reported no effect of the addition of color (red, blue, yellow,

and green) when compared to a clear, no-color-added

baseline on participants’ ratings of the sweetness of either

sweetened water or gelatine samples. Similarly, Frank et al.

(1989) reported that adding red food coloring to either an

odorless or strawberry odor-sweetened aqueous samples

failed to increase perceived sweetness ratings of the orange

red-looking drinks relative to participants’ assessment of the

clear drinks. Note that the participants in this latter study had

to rate the intensity of 16 stimuli on a 21-point sweetness

scale: the stimuli were generated by crossing the factors of

sweetness intensity (four levels), color (present vs. absent),

and odorant (present vs. absent). In other words, half of the

drinks in this study were uncolored. This raises the possibility

that the inclusion of so many sweetened but uncolored

solutions might have helped participants to realize that the

color was not necessarily predictive of the presence/intensity

of the taste. A similar explanation could, of course, also be

put forward to account for the null results reported by Alley

and Alley (1998). Zampini et al. (2007)alsofailedto

demonstrate an easily interpretable effect of variations in

color intensity on perceived sweetness intensity using a

labeled magnitude scale rating procedure.

Thus, with regard to the question of whether or not adding

color to an otherwise colorless substrate influences the

perceived intensity of differen t basic tastes, the answer appears

to depend on a number of factors including the particular taste

under investigation (Maga 1974) and perhaps the precise

presentation protocol adopted (such as how many incongru-

ently colored trials the participant may be presented with; see

footnote 4). Certainly , magnitude estimation typically gives

rise to more pronounced effects than other methods (though

see Giffo rd and Clydesdale 1986 for one null effect of color on

salt perception reported using the magnitude estimation

technique). The consensus view would currently seem to be

that color cues do not influence the perception of saltiness (see

Chan and Kane-Martinelli 1997; Gifford and Clydesdale 1986;

Gifford et al. 1987;Maga1974). By contrast, the perception

of sweetness can be modified by the addition of red (or green)

food coloring (e.g., see Johnson et al. 1982, 1983; Kostyla

1978; Lavin and Lawless 1998; Pangborn 1960), but

importantly, this effect is not always observed (Alley and

Alley 1998; Frank et al. 1989; Johnson

1982;McCulloughet

al. 1978; Pangborn 1960). Null effects are often reported in

studies in which colored drinks are compared to clear drinks

(though see Zampini et al. 2007 for an exception).

Taken at face value, these results would appear to

suggest that color does indeed influence people’s percep-

tion of taste intensity. However, under closer examination,

many of the findings reported above are potentially

problematic. For example, in their description of the

threshold task, Johnson and Clydesdale (1982) make no

reference to interleaving any “catch trials” in which

unsweetened solutions were mixed in with the sweetened

solutions. This is unfortunate because of the susceptibility

to response bias; that is, it could be argued that the presence

of the coloring in certain solutions simply l ed the

participants in those studies to expect a taste to be present,

and thus, they were more willing to respond that they did

indeed perceive a taste (cf. Engen 1972; Odgaard et al.

2003). It is important to note that the magnitude estimation

procedure is also vulnerable to demand characteristics; that

is, participants could easily be influenced by the coloring

such that their responses, rather than their actual taste

percepts, changed in response to changes in the color

intensity of the solutions (indeed, it seems possible that

under certain conditions, participants may simply want to

please the experimenter). Using signal detection techniques

(e.g., see Green and Swets 1966) could help separate out

perceptual from decisional effects here.

3

Due to space

constraints, detailing each of the various factors that might

help account for the occurrence of false positive results

(if that is what Johnson and colleagues’ results actually

reflect) lies beyond the scope of the present paper; for

instance, the specific tasks and ranges of stimuli used in

each study, as well as the demand characteristics of each

experiment and differences in the pools of participant

tested, might all be expected to influence participants’

expectations (see Shankar et al. 2009), which could, in turn,

have influenced the pattern of results that were observed.

Does food color influence flavor intensity? As visual

inspection of Table 1 makes clear, there have been far fewer

studies of color’s influence on perceived flavor intensity.

However, in contrast to the rather mixed picture regarding

the effect of color on taste intensity, the story concerning

color’s effect on flavor intensity seems much more clear-cut

and convincing. In one of the most frequently cited studies

in this area, DuBose et al. (1980) reported that overall flavor

intensity was affected by color intensity, with higher color

intensity solutions giving rise to stronger flavor evaluation

3

Perceptual effects are usually defined in terms of a change in

perceptual sensitivity, such as a change in the d′ measure that can be

derived using signal detection theory (e.g., Green and Swets 1966).

By contrast, changes in decisional criteria, possibly reflecting a

response bias or change in the criteria for responding adopted by

participants (such as, for example, participants simply being more

likely to respond that a flavor, odor, or taste is present whenever a

color is added to a liquid; see Engen 1972), may show up in one’s

measure of bias (c or beta).

72 Chem. Percept. (2010) 3:68–84

responses by participants for orange- (but not for the cherry-)

flavored beverages. Meanwhile, Kostyla (1978)reportedthat

the addition of yellow color to sweetened cherry-, raspberry-,

and strawberry-flavored beverages decreased flavor ratings

by around 4%. Blue color reduced fruit flavor by 20% (and

the addition of red coloring increased sweetness by 5–10%).

Elsewhere, significant effects of color on flavor intensity have

also been reported by Romeu and De Vicente (1968). More

complex results have been reported in other studies where

certain color–flavor combinations appear to give rise to bigger

effectsthanothers(Bayarrietal.2001), and null results of

varying the intensity of the color on flavor intensity are rarer

(Zampini et al. 2007, 2008).

It should be noted here that people are very poor at

identifying orthonasally presented odors in the absence of any

other sensory cues regarding the odor’s identity (e.g., Cain

1979; Desor and Beauchamp 1974;Engen1972; Eskenazi et

al. 1986; Jönsson et al. 2005; Zellner et al. 1991). By contrast,

people appear to be much better at identifying the presence of

the basic tastes (e.g., sweet, sour, salty, and bitter; see

Bartoshuk 1975; Laing et al. 2002). A priori, then, it would

seem likely that participants’ judgments of odor (and hence of

flavor) identity would be much more likely to be influenced

by the presentation of an incongruent visual color cue than

would their judgments of the identity of a specific tastant.

Indeed, robust effects of color cues on judgments of odor

intensity have now been reported in numerous studies (e.g.,

Blackwell 1995; Davis 1981; Engen 1972; Morrot et al.

2001; Parr et al. 2003; Zellner and Kautz 1990; Zellner and

Whitten 1999). For example, Zellner and Whitten reported

that the addition of color (presented at one of four different

color intensity levels) influenced participa nts’ odor intensi-

ty responses when orthonasally sniffing red strawberry and

green mint solutions. Interestingly, ratings of the intensity

of the strawberry odor peaked at the middle color intensity,

while for the mint odor, there was a monotonic increase

with increasing color intensity. In a subsequent experiment,

Zellner and Whitten show ed that while the intensity of the

color played a large role in modulating perceived odor

intensity, the specific color that was added (be it appropriate

or inappropriate) had little effect. Given results such as these,

it would seem likely that color should also influence flavor

intensity judgments. That said, however, most of these

crossmodal studies involved investigating the effect of color

on participants’ orthonasal odor judgments. In this regard,

the results of a study by Koza et al. (2005) are critical. For

example, they demonstrated that while the addition of color

resulted in an increase in the perceived intensity of

orthonasally presented odors, it actually led to a reduction

in the perceived intensity of the very same odors when

presented retronasally (i.e., as they would be if participants

were making flavor judgments; see also Christensen 1983;

Zellner and Durlach 2003

).

It is worth noting that researchers who have documented

null resul ts of the addition of food coloring on ratings of

taste and/or flavor inte nsity have rarely bothered to conduct

any kind of analysis to ensure they had sufficient power in

their ex perimental design to observe a significant effect had

one been present (see Frick 1995). Because of the nature of

flavor research, the number of trials a given participant can

complete tends to be rather limited,

4

hence constraining the

ability of experimenters to detect what may well be a

relatively small behavioral effect (see also Lecoutre and Derzko

2001; Rouanet 1996). Complicating this issue even further is

the fact that the effects of food coloring on ratings of taste and

flavor intensity , or on the detection of the presence of a tastant

in solution, appear to be rather stimulus-specific (e.g., see

Bayarrietal.2001;Maga1974; Zampini et al. 2007, 2008).

Note that a similar stimulus specificity has also been reported

previously for the case of olfactory–gustatory interactions

(e.g., see Frank and Byram 1988; though see also Valentin et

al. 2006). It is therefore currently unclear whether the discre-

pant results of color on taste intensity reporte d by dif ferent

groups of researchers over the last 50 years are best explained

in terms of a failure to properly control for all of the potential

confounding variables or by a lack of statistical power in the

experimental designs used by certain researchers in the field;

plausible arguments can be made in both directions.

Does Food Color Influe nce Perceived Flavor Identity?

By contrast, many (and, in fact, we would argue all) studies

published to date support the claim that judgments of flavor

identity are influenced by a food’s color (e.g., DuBose et al.

1980; Hall 1958; Institute of Food Technologists 1980;

Kanig 1955; Levitan et al. 2008;Moir1936;Sakai2004;

Shankar et al. 2009;Stillman1993; Zampini et al. 2007,

2008; see also Dolnick 2008; note that we are aware of no

studies that have examined the effect of food color on taste

identification, and hence in this section, we only discuss

studies of color’s influence on flavor identification). By

contrast, several studies have investigated the effect of color

on orthonasal olfactory odor identification judgments. So, for

example, Zellner et al. (1991) have shown that participants

correctly identify odors more rapidly when colored appro-

priately than when uncolored or else inappropriately colored.

4

Note here also that many of the demonstrations of the influence of color

on taste and/or flavor in the literature have actually been reported in those

studies in which the participants were only given a very small number of

stimuli to evaluate (e.g., five or less stimuli in certain of the experiments

reported by DuBose et al. 1980; Hoegg and Alba 2007b;Hyman1983;

Lavin and Lawless 1998;Morrotetal.2001;Orametal.1995; Stillman

1993;or6–15 stimuli in the studies reported by Alley and Alley 1998;

Shankar et al. 2009). This may be particularly important as people

appear to quickly learn that the color of a beverage no longer predicts a

particular taste (see Stevenson et al. 2000).

Chem. Percept. (2010) 3:68–84 73

In terms of studies looking at color’s effect on flavor

identification, DuBose et al. (1980) conducted one fre-

quently cited study addressing this question. The partic-

ipants in their study attempted to identify the flavors of a

variety of differently colored fruit-flavored drink s. Certain

color–flavor pairings were deemed “appropriate” (e.g., a

cherry-flavored drink colored red), while others were

deemed “inappropriate” (e.g., as when the lime-flavored

drink was colored red; though see Shankar et al. 2009 on

the notion of appropriateness). DuBos e et al. found that

participants misidentified the flavor of a number of the

drinks when the coloring was inappropriate. What is more,

participants’ incorrect answers often seemed to be driven by

the colors of the drinks themselves. That is, the participants

often made what could be classed as visually dominant

responses (see Partan and Marler 1999; Posner et al. 1976).

So, for example, 26% of the participants reported that a

cherry-flavored drink tasted of lemon/lime when colored

green as compared to no-lime-flavor responses when the

drink was colored red instead (see Table 3 for a summary of

the results from one of the experiments conducted by

DuBose et al.).

One potentially important limitation with regard to the

interpretation of the study of DuBose et al. (1980 ), and, in

fact, with the majority of other studies that have investi-

gated crossmodal influences of food coloring on flavor

perception in humans (e.g., Hall 1958; Kanig 1955; Moir

1936; Oram et al. 1995), is that the participants were not

informed of the deception that was taking place (e.g., see

Hall 1958, p. 229). This is a particularly important issue

given that it means that the participants in the majority of

the studies that have investigated the effect of color on

flavor identification may simply have assumed that the

colors of the drinks were meant to be informative with

regard to their likely flavor. In other words, if participants

found it difficult to discriminate the identity of the flavor

(or taste) on the basis of gustatory, olfactory, and/or flavor

cues, then they may simply have decided to respond on the

basis of the more easily discriminable color cues instead.

Hence, it is enti rely possible that the participants in these

studies may simply have used the salient visual cues as a

cognitive shortcut with regard to the likely flavors of the

foods that they were being asked to evaluate (cf. Bertelson

and Aschersleben 1998 for a similar confound that has been

identified in the literature documenting the visual capture,

or dominance, over perceived auditory localization). That

is, the participants in these earlier studies of multisensory

flavor perception may have felt some pressure to respond in

line with the salient information provided visually (namely,

the obviously changing color of the drink from one trial to

the next; cf. Orne 1962 ). As such, it is unclear whether the

results reported in many of the early studies demonstrating

color’s influence on flavor identification responses reflect a

response bias elicited by the clearly visible (and changing)

colors of the drinks that were presented to the participants,

a genuine crossmodal perceptual effect (i.e., meaning that

the color cues actually modulated the flavor percept itself;

see Green and Swets 1966; Hoegg and Al ba 2007a), or

some unknown combination of these two effects (see below

for a fuller discu ssion of this issue).

5

One means by which researchers have attempted to

circumvent (or at least reduce) this potential uncertainty

regarding the cause of color’s influence on flavor identifi-

cation responses is by explicitly informing their participants

of the potential deception prior to the start of the study (see

Stillman 1993; Zampini et al. 2007, 2008 ). Although only a

few studies have, to date, taken this precaution, the results

nevertheless confirm the suggestion that food color ing can

still affect people’s flavor identification responses under

such conditions. For example, the 310 untrained observers

(visitors to an open day at the University of Auckland) in a

study reported by Stillman (1993) were each given a

Table 3 Partial summary of the results from DuBose et al. (1980)

(experiment 2)

Reported flavor Color of drink

Red (%) Orange (%) Green (%)

Cherry 70 41 37

Orange 0 19 0

Lime 0 0 26

The results highlight the profound effect that food coloring can have

on participants’ flavor identification responses. The participants in this

study had to try and identify 16 different sequentially presented

beverages created by fully crossing the factors of flavor (cherry-,

orange-, or lime-flavored, or flavorless) and color (red, orange, green,

colorless). The participants were given a checklist of 14 possible

responses (including 12 fruit flavors) to choose from when trying to

identify each of the drinks (strawberry, raspberry, lemon, lime, grape,

apple, cherry, orange, blueberry, lemon lime, grapefruit, apricot, other,

or no flavor). The table highlights the distribution of responses from

the three most common flavor responses for the cherry-flavored drink.

The numerical values indicate the percentages of each flavor response

for each color

5

Note that we do not wish to argue that decisional biases in the

context of food colorings’ influence on multisensory flavor perception

are not, in and of themselves, interesting. They most certainly are. Our

point here is rather that the decisional biases that are elicited not

simply by the color of the foodstuff itself, but rather by the

ecologically invalid context in which the participants in these

laboratory studies often find themselves, may not be especially

informative (see also Garber et al. 2001, 2003 for a similar argument).

Our concern is that the results of such studies may say more about

how participants respond when placed in an ecologically invalid

laboratory context than they do about color’s influence on flavor

perception in the real world.

74 Chem. Percept. (2010) 3:68–84

beverage to taste and identify and were informed that its

color was independent of the flavor. The drinks were either

raspberry- or orange-flavored and were either colored red,

yellowish orange, green, or else left uncolored. The results

(see Fig. 2) showed that participants were significantly

better at correctly ident ifying the raspberry flavor when the

drink was colored red than when it was colored green,

orange yellow, or else was presented as a colorless solution.

The orange-flavored solution was identified significantly

more accurately when the drink was colored orange, yellow,

or red than when it was presented as a colorless solution.

The participants in another study reported by Zampini

et al. (2007; experiment 2) were also explicitl y informed

that there was no relationship between the color and flavor

of the drinks that they had to evalua te. That is, they were

informed that each of the 124 drinks that they had to

sample was just as likely to appear as a c olorless solution,

or as a red, green, orange, yellow, blue, or gray solution,

regardless of its actual flavor. Even though Zampini et al.’s

participants were clearly aware that the colors of the

drinks that they were tasting were not in any way

informative (cf. Engen 1972), the colors of the drinks

nevertheless still exerted a significan t influence on parti-

cipants’ flavor identification responses (see Fig. 3). Similar

results were also reported in a follow-up study (Zampini

et al. 2008) in which the participants had to try and identify

the f lavor of blackcurrant, orange, and flavorless solutions

that had been colored yellow, gray, orange, red, or else left

colorless (see Fig. 4). Taken together, the results of

Zampini et al. ’s(2007, 2008) studies therefore add weight

to the cla im that the crossmoda l effect of color on multi-

sensory f lavor perception in humans does not reflect

task demands or any simple form of decisional bias (cf.

Delwiche 2004;HoeggandAlba2007b).

Interim Summary

In summary, then, many studies over the last 70 years or so

have provided empirical support for the claim that the color

of a food/drink can exert a powerful influence on people’s

flavor identification responses (e.g., DuBose et al. 1980;

Hall 1958; Kanig 1955; Levitan et al. 2008; Moir 1936;

Oram et al. 1995; Shankar et al. 2009; Stillman 1993;

Zampini et al. 2007, 2008). What is more, we are not aware

of any studies that have reported results that conflict with

this claim—i.e., where the color of a food was (noticeably)

changed but where this change had no effect on partic-

ipants’ flavor identification responses.

6

As such, we would

argue that Lavin and Lawless’s(1998, p. 284) claim that

“the literature on the effects of color on taste and flavour

judgments is consistent in its inconsistency” is incorrect for

at least as far as the effects of food coloring on people’s

flavor identification responses are concerned, the answer

appears clear-cut: food coloring most certainly does

influence people’s flavor identification responses.

Here, though, it is also important to bear in mind that

one does not tend to see complete visual dominance

(sometimes known as ‘capture’). That is, participants’

flavor identification responses do not always match the color

that they see. Instead, researchers typically report a visual

biasing of participants’ responses on a certain proportion of

the trials, with the exact proportion varying from one study

to the next. So, for example, DuBose et al. (1980)showed

that atypically colored drinks were identified by their color

on 40% of the trials and by their flavor on 28% of the trials.

Meanwhile, the participants in Stillman’s(1993) study were

able to correctly identify the flavor of the drink in 60% of

trials. Oram et al. (1995) reported that for adults tested in

their study, responses were based on color on 13% of trials

and on flavor on 79% of trials. We discuss possible reasons

for this discrepancy below.

Perceptual vs. Decisional Contributions to Color’s

Influence on Flavor Identification

None of the studies reported thus far bear directly (and

unequivocally) on the question of whether these cross modal

effects on participants’ flavor identification responses

reflect a decisional effect, a perceptual effect, or some

1

*

*

0.8

0.6

Uncoloured

0.4

Red

Orange

0.2

Green

0

Proportion correct

Raspberry Orange

Flavour of the solution

Fig. 2 Summary of the results of Stillman’s(1993) study in which

310 participants were given a single drink to taste and identify. The

horizontal lines indicate those comparisons between conditions that

were significant (asterisk) using independent samples chi-square tests

6

The one exception to this claim comes from one of the conditions in

Zampini et al.’s(2007, Experiment 2) study in which participants’

flavor identification responses for the strawberry-flavored solutions

were not significantly affected by the changes that were introduced

into the colors of the drinks. However, given that the numerical trends

were in the appropriate direction, this null result may simply reflect a

lack of statistical power.

Chem. Percept. (2010) 3:68–84 75

unknown combination of the two. One problem here in

terms of trying to answer this question is that there are no

simple means of assessing perceptual sensitivity (such as

the d′ measure that is afforded by signal detection theory;

Green and Swets 1966) when participants are allowed to

make unconstrained flavor identification responses, as often

happens when one is trying to identify a food’s flavor in

natural settings. While it is certainly true that techniques do

exist to try and counteract the contribution of any guessing

biases that may be present (see Chen and Spence 2010 ;

Intraub 1984), no one has as yet used them in order to try

and isolate any genuinely perceptual contribution to color’s

influence on participants’ flavor identification responses

(see also O’Mahony 1992).

As such, all that can be said with any confidence at the

present time is that all of the studies that have been

published to date (no matter whether using a free respond-

ing or forced choice discrimination task) have shown a

100

LIME FLAVOR

a)

7575

5050

Correct responses (%)

25

0

Colorless

Green-

standard

Green-

double

Orange-

standard

Orange-

double

Red-

standard

Red-

double

Color of the solutions

100

ORANGE FLAVOR

b)

100

7575

50

25

Correct responses (%)

0

Colorless

Green- Green-

double

Orange-

standard

Orange-

double

Red-

standard

Red-

doublestandard double standard double standard double

Color of the solutions

Fig. 3 Summary of the results of the study of Zampini et al (2007)

(experiment 2) documenting the effect of color on flavor identifica-

tion. Lime, orange, strawberry, and flavorless drinks were presented

either colored green, orange, red, or colorless in a fully counter-

balanced design. Either a standard or double intensity of the colorant

was added to the solutions. The participants had to try and identify the

flavor of each drink from a list of 22 alternatives (if the participants

indicated the “other” option they were prompted to suggest the

specific flavor they had in mind) and also rate the flavor intensity.

They were given 124 samples to evaluate in total using a sip-and-spit

method. Coloring the solutions congruently (e.g., green for lime, red

for strawberry, and orange for orange) led to a modest increase in the

number of correct flavor identification responses for the strawberry-

and orange-flavored drinks (relative to the performance seen when

participants judged the colorless solutions). Incongruent coloring

impaired the participants’ ability to identify the orange- (when colored

green or red) and lime-flavored solution (when colored orange or red).

Overall, color appeared to have less of an impact on the identification

of the strawberry solutions. At present, there is no obvious explanation

for this particular result. Note also that it is difficult to discern any

clear pattern of results from the doubling of the intensity of the food

coloring added to the various solutions

76 Chem. Percept. (2010) 3:68–84

crossmodal effect of color on participants’ flavor identifi-

cation responses. Whether this reflects a genuine perceptual

effect, a predom inantly decisional effect, or some unknown

combination of the two effects will only be resolved by

future research. Progress here will likely come through the

use of more sophisticated psychophysical paradigms (e.g.,

see Odgaard et al. 2003 for such an approach being applied

to the auditory modulation of visual brightness judgments;

see also Lau et al. 1995). It is also possible that a definitive

answer to the question of whether or not color’s crossmodal

influence on flavor identification occurs at a perceptual

level may be assisted by the evidence emerging from

cognitive neuroscience research. It would, for example, be

interesting to know whether the neural activity in primary

(or possibly secondary) gustatory cortex and perhaps more

interestingly in orbitofrontal cortex elicited by a gusta tory/

olfactory/flavor stimulus ca n be chan ged simply b y

changing a food or drink’s color (cf. González et al. 2006;

McClure et al. 2004; Österbauer et al. 2005; Small 2004;

Veldhuizen et al. 2009; Verhagen and Engelen 2006). Such

effects, sho uld they be observed, would certainly be

consistent with the existence of at least some perceptual

component to the crossmodal effect of color on flavor

perception. Given that such top-down effects have recently

been observed on the basis of verbal food/taste descriptors

(e.g., Nitschke et al. 2006; Sarinopoulos et al. 2006), we are

optimistic that they might also be found here (that is, for the

case of visual color cues).

Expectancy-Based Effects of Food Coloring

It seems likely that whenever we see a food of a certain

color, that color, together with any other contextual cues (e.g.,

100

STRAWBERRY FLAVOR

c)

7575

5050

25

Correct responses (%)

0

Colorless

Green-

standard

Green-

double

Orange-

standard

Orange-

double

Red-

standard

Red-

double

Color of the solutions

100

FLAVORLESS

d)

100

7575

50

25

0

Colorless

Green- Green-

double

Orange-

standard

Orange-

double

Red-

standard

Red-

doublestandard double standard double standard double

Color of the solutions

Correct responses (%)

Fig. 3 (continued)

Chem. Percept. (2010) 3:68–84 77

is it a food or drink item, hot or cold, transparent or opaque,

etc; what Francis 1977, describes as “visual appearance”

cues), will lead us to generate specific expectations regarding

the likely flavor of that food (see Cardello 2007;Kochand

Koch 2003; Lee et al. 2006; Levitan et al. 2008;Shankaret

al. 2009; Yeomans et al. 2008; Zellner and Durlach 2003).

Zampini et al. (2007) (experiment 1) recently investigated

the nature of these crossmodal associations by showing

participants (all from the UK and of UK origin) a range of

colored drinks (green, orange, yellow, blue, gray, red, and

colorless) and asking them to look at each drink in turn and

simply report (without tasting) what flavor they would

expect it to have. The results (see Table 4)showedthatall

of the colored drinks generated systematic expectations

regarding a drink’s likely flavor. It is our belief that such

color-induced flavor expectations (what Hutchings 1977 called

“anticipatory” effects) may lead to the “misidentification” of

flavors when a drink is subsequently tasted (cf. Stevenson and

Oaten 2008). Misidentification at this (cognitive) level will

presumably also provide access to a wealth of semantic

information about the “misidentified” flavor (see Engen

1972; Gottfried and Dolan 2003; Jönsson et al. 2005;

Marques 2006;Morrotetal.2001;Parretal.2002; Revonsuo

1999; Skrandies and Reuther 2008; Zellner et al. 1991),

which in turn might reasonably be expected to influence

participants’ judgments/responses. This misidentification

may then have perceptual (i.e., as well as decisional)

consequences (see also Williams et al. 1984a, b). Here, one

need only think of the placebo effect where a person’sbeliefs

(be they induced by the color of a pill or verbal labeling)

have bee n shown to have surprisingly low-level (i.e.,

perceptual) effects (de Craen et al. 1996; Plassmann et al.

2008;Shivetal.2005).

Regarding the expectancy-based account of color

’s

influence on multisensory flavor perception, it is interesting

to note that red, one of the colors that have often been shown

to generate strong expectations concerning a food’staste,

odor, and flavor (e.g., Koch and Koch 2003;O’Mahony

1983; see also Demattè et al. 2006), also happens to be one

of the colors that are most often reported as having an effect

in terms of influencing flavor, taste, and odor perception (in

terms of both identity and intensity judgments; e.g., Hyman

1983; Johnson and Clydesdale 1982;Maga1974;Morrotet

al. 2001;Orametal.1995; Stillman 1993;seeFig.2). It

should, however, also be noted that different colors will

likely lead to the generation of different taste/flavor expecta-

tions by different people as a function of their background

and/or culture (Shankar et al. 2009; see also Scanlon 1985),

expertise/experience with tasting a particular foodstuff

(e.g., Pangborn et al. 1963; Parr et al. 2003; Smith 2007;

Urbányi 1982; Williams et al. 1984a, b; though see also

Table 4 Results of the study of Zampini et al. (2007) (experiment 1)

asse ssing the flavor expectations generated by a group of UK

participants on being presented with clear plastic beakers containing

transparent drinks that had been colored green, orange, yellow, blue,

gray, red, or left colorless

Color of

drink

Expected flavor (% of participants with that

expectation)

Green Lime (69%), apple (20%), melon (11%)

Orange Orange (91%), aniseed (5%), toffee (4%)

Yellow Lemon (89%), pear (5%), apple (4%), melon (2%)

Blue Spearmint (86%), raspberry (9%), cream soda (5%)

Gray Blackcurrant (53%), licorice (40%), cherry (4%),

aniseed (4%)

Red Strawberry (46%), raspberry (27%), cherry (27%)

Colorless Flavorless (51%), cream soda (16%), vanilla (15%),

aniseed (15%), spearmint (2%), melon (2%), pear (2%)

The table shows the percentage of trials in which participants reported

that they expected a particular colored drink to taste of a certain flavor

100

Orange

75

50

25

Correct responses (%)

0

Yellow Grey Orange Red Colorless

Color of the solution

100

Blackcurrant

7575

50

25

00

Yellow Grey Orange Red Colorless

100

Flavorless

75

50

25

0

Yellow Grey Orange Red Colorless

Correct responses (%)Correct responses (%)

Color of the solution

Color of the solution

Fig. 4 Summary of the results of the study of Zampini et al. (2008)

highlighting the crossmodal effect of color on participants’ flavor

identification responses. Once again, a sip-and-spit method was used

78 Chem. Percept. (2010) 3:68–84

Teerling 1992), and age (Oram et al. 1995; Philipsen et al.

1995; see also Lavin and Lawless 1998).

Shankar et al. (2009) recently investigated the nature of

any cross-cultural differences in color–flavor expectancy

effects. The two groups of participants in their study, one

from the UK the other from Taiwan, were shown seven

colored drinks (brown, blue, yellow, orange, green, clear,

and red) and had to report on the flavor that they expected

each colored drink to taste of. Just as in the study of

Zampini et al. (2007), the participants in each group were

found to generate consistent flavor expectations based on

the colors of the drinks. Importantly, however, the flavor

expectations generated by the two groups of participants

were significantly different for several (but importantly, not

all) of the colored drinks (see Table 5).

Given the individual differen ces in the fl avo r expect-

ations generated by viewing a food’s col oring, a critical

experiment t hat has yet to be conducted would involve

investigating whether the flavor expectations held by an

individual do indeed lea d to the misi dentific ation of a

food or drink ’s flavor or aroma. Our prediction is that if

one p erson expects a brown drink to taste of cola while

another expects a d rink of the same color to ta ste of grape

(see Ta ble 5; see also Oram et al. 19 95), then adding a

brown color to a drink should result in different flavor

(aroma) identification responses for thes e two individu-

als. While th is experiment sounds (and indeed is) ve ry

simple, no o ne has, as yet, me asured their participants’

flavor (or for that matter taste or odor) expectations and

then followed through to investigate whether those

expectations do indeed predict the subsequent pattern of

flavor (t aste or odor ) misidentification that results when

that color is added to a foodstuff (cf. Cardello 200 7;

Shankar et al., submitted).

While some researchers appear to believe that such

cognitive effects of color on flavor will not have any low-

level (e.g., physiological/perceptual) consequences (e.g.,

see Keast et al. 2004; Fig. 1 ), others clearly think that

color’s influence on flavor is perceptual in nature (e.g., see

Delwiche 2004;Fig.1). Discussion here though is

complicated by the fact that different researchers appear to

use the same terms (e.g., “perceptual”) to mean very

different things. For example, while Delwiche (2004)

(Fig. 1) draws a clear distinction between cognitive and

perceptual effects, others appear to view cognitive/expecta-

tion effects as being perceptual (as opposed to physical,

sensory, or hedonic; see Cardello 1996; Fig. 1). It is

therefore important to note that expectancy effects (here

one can also think of labeling, pricing, and/or branding as

forms of expectancy effect; e.g., Cardello 1994, 2007;

Hutchings

1977; Shiv et al. 2005; though see Davis 1981)

have been shown in neuroimaging studies to have surpris-

ingly early effects on sensory information processing in

humans (e.g., McClure et al. 2004; Nitschke et al. 2006;

Plassmann et al. 2008; Sarinopoulos et al. 2006). Such

results therefore raise the possibility that color-induced

expectancy effects might also influence a person’s percep-

tual representation of flavor information and not just the

response that they happen to make.

Color-induced expectancy effects might influence flavor

perception (in particular, identification) by directing a

participant’s attention to a salient component of a flavor

stimulus (e.g., Ashkenazi and Marks 2004; Marks 2002;

Marks and Wheeler 1998; Marshall et al. 2006; Oram et al.

1995). Research elsewhere in psychology has shown that

the focusing of a participant’s attention on a particular

stimulus or stimulus attribute can enhance the perceptual

representation of that stimulus or stimulus attribut e (i.e.,

can have an effect on perceptual sensitivity as measured by

a change in d′). It is, though, important to bear in mind that

color cues can (and do) sometimes lead to decisional effects

as well (e.g., by influencing people’s criteria for making

various judgments; cf. Engen 1972; McCullough et al.

1978). Such decisional effects are likely to be especially

prominent when the stimulus itself is ambiguous (as flavor

stimuli often are; cf. Chaiken 1980; Wilson and Klaaren

1992). Taken together, the research reviewed in this section

therefore supports the view that “higher level” (or top-

down) cognitive beliefs or expectations can (and do) have

low-level (early) effects.

The Multisensory Integration of Color/Flavor Cues

One of the most important issues for future research

concerns the question of whether in addition to any top-

down cognitive influence (in the form of expectancy

effects), food coloring can also influence flavor identifica-

tion in humans (automatically) in a b ottom-up manner via

multisensory integration. The mul tisensory integration of

flavor cues in a food or drink with an atypical visual color

cue would be expected to lead to a form of sensory (i.e.,

visual) dominance over flavor perception (see Ernst and

Banks 2002; Ernst and Bülthoff 2004; Posner et al. 1976;

Spence 2008). Numerous neurophysiological studies have

already demonstrated the integration of olfactory, gustatory,

textural, and visual cues in the orbitofrontal cortex of both

monkey and man (see Gottfried and Dolan 2003; Österbauer

et al. 2005; Rolls and Baylis 1994; Rolls et al. 1996). Given

that the Bayesian approach is currently proving so

successful elsewhere in the study of multisensory integra-

tion, one might expect this approach to understanding

multisensory perception to have an influence here as well

soon. However, the problem that one soon runs into in

terms of trying to separate top-down (i.e., cognitive) and

bottom-up (i.e., stimulus-driven) influences is that many of

Chem. Percept. (2010) 3:68–84 79

the factors that are likely to promote top-down cognitive

effects are also likely to increase the likelihood of bottom-

up multisensory integration as wel l (see Spence 2007 on

this point).

Isolating the Bottom-Up Effects of Color on Flavor

Perception

In the future, though, it may be possible to isolate any

bottom-up effects of color on flavor perception by utilizing

articulatory suppression to minimize the effect of top-down

cognitive facto rs on participants’ performance. For in-

stance, Stevenson and Oaten (2008) recently used this

technique in order to investigate whether color’s effect on

orthonasal olfaction is automatic or not. The cherry and

strawberry olfactants used in this study were dissolved in

liquids that were colored green, red, or else left colorless.

Stevenson and Oaten demonstrated that the crossmodal

influence of color (either appropriate or inappropriate) on

odor discrimination performance was significantly reduced

when their participants engaged in articulatory suppression

(saying the word “the” out loud repeatedly) while evaluat-

ing the odors. This result suggests that the crossmodal

effect of color on odor perception is not mandatory (or, in

Stevenson and Oaten’s words, “automatic”). As such, it

provides some evidence against color influencing odor

perception through a process of bottom-up mul tisensory

integration (perhaps leading to sensory dominance) since

research in other areas of psychology has shown that

multisensory integration tends to be relatively automatic

(i.e., unaffected by the performance of a secondary task;

see Navarra et al. 2009; Santangelo and Spence 2008 for

reviews).

It would, of course, be ideal to utilize the articulatory

suppression technique in order to assess whether one can

eliminate (or at least modulate) color’s crossmodal effect on

flavor identification.

7

If one were to obtain a similar result

to that reported by Stevenson and Oaten (2008), it would

provide eviden ce that color’s influence on flavor perception

is mediated primari ly by cognitive (or top-down) expectan-

cy factors and not by bottom-up (i.e., automatic) multisen-

sory integration. One might think such a result likely given

Stevenson and Oaten’s use of food odors. However, it is

important to note that Koza et al. (2005) have shown that

color can have qualitatively different effects on olfactory

perception as a function of whether an odor is delivered

orthonasally (as in Stevenson and Oaten’s study) or

retronasally (as when actually consuming a food or drink).

Alternatively, howe ver, one may also be able to dissociate

Table 5 Results of the cross-cultural study of Shankar et al. (2010) assessing the flavor expectations elicited by differently colored drinks in two

groups of participants, one from the UK, the other from Taiwan

The table highlights the three most commonly expected flavor responses (chosen by more than one participant). The shaded rows indicate the

colored drinks (brown, blue, yellow, and orange) that elicited significantly different flavor expectations from the two groups of participants

7

Though, of course, there may be some practical challenges

associated with trying to taste a colored solution while at the time

speaking out loud. One could though instead ask the participant to

read out a list of words silently in their head or else to engage in some

other highly attention-demanding task, for example, monitoring a

rapid serial visual presentation stream for occasionally presented

targets (e.g., see Santangelo and Spence 2008).

80 Chem. Percept. (2010) 3:68–84

bottom-up multisensory integration effects from top-down

effects resul ting from cognitive expectancies by playing

with the parameters of stimulus presentation, such as by

varying the timing and/or spatial relationship between the

color and the flavor (see also Lee et al. 2006). Bottom-up

integration tends to be more sensitive to spatiotemporal

coincidence of the constituent signals than are top-down

cognitive effects (see Spence 2007).

It may, of course, turn out that the crossmodal effect of

food coloring on flavo r identification operates in both a top-

down manner via cognitive expectations and in a bottom-up

manner via the sensory dominance resulting from the

automatic (i.e., involuntary) multisensory integration of

the various unimodal sensory signals. Complicating matters

further here though is the fact that the relative contribution

of top-down and bottom-up factors might also vary as a

function of the speci fic combinations of color (and other

visual appearance cues; Francis 1977; Levitan et al. 2008)

and flavor being investigated. On the one hand, the more

that a color is associated with a particular taste or flavor

(such as red being associated with sweetness in ripe fruits

and green with tartness/sourness in unripe fruits; Maga

1974; Pangborn 1960), the stronger one might expect that

both the bottom-up and top-down effects should be. By

contrast, the consequences of marketing, for example, the

recent introduction of the association between blue coloring

and raspberry flavoring (see Garber et al. 2008; Shankar et

al. 2010; see also Triplett 1994), might, at least initially, be

expected to have a primarily cognitive effect.

Having demonstrated that food coloring does indeed

influence flavor identification, the question of how best to

unravel the various mechanism(s), at both a behavioral and

neural level, underlying this crossmodal effect clearly

represents an important and challenging area for study in

the years to come. Part of the challenge here comes from

the fact that (as shown in Fig. 1) it is currently unclear

whether color’s crossmodal influence on flavor perception

in any given situation is being driven by color’s influence

on taste, smell (orthonasal or retronasal), or directly on the

flavor percept itself. What is, though, certain at the present

time is that color plays an integral part in our experience of,

and responses toward, food and drink even if, as suggested

by the ISO (1992, 2008), visual cues do not constitute a

core attribute of flavor perception.

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Maya U. Shankar & Massimiliano Zampini

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