Does the colour of the mug influence the taste of the coffee?
In experiment 1, the white travel mug enhanced the rated “intensity” of the coffee flavour relative to the transparent mug. However, given slight physical differences in the mugs used, a second experiment was conducted using identical glass mugs with coloured sleeves. Once again, the colour of the mug was shown to influence participants’ rating of the coffee. In particular, the coffee was rated as less sweet in the white mug as compared to the transparent and blue mugs.
Both experiments demonstrate that the colour of the mug affects people’s ratings of a hot beverage. Given that ratings associated with the transparent glass mug were not significantly different from those associated with the blue mug in either experiment, an explanation in terms of simultaneous contrast can be ruled out. However, it is possible that colour contrast between the mug and the coffee may have affected the perceived intensity/sweetness of the coffee. That is, the white mug may have influenced the perceived brownness of the coffee and this, in turn, may have influenced the perceived intensity (and sweetness) of the coffee. These results support the view that the colour of the mug should be considered by those serving coffee as it can influence the consumer’s multisensory coffee drinking experience. These results add to a large and growing body of research highlighting the influence of product-extrinsic colour on the multisensory perception of food and drink.
In Australia alone, around a billion cups of coffee are consumed in cafés, restaurants and other outlets each and every year. Even Britain, a nation famous for its fondness for tea, has, in recent years, seen a dramatic rise in its coffee consumption, with an estimated 70 million cups drunk each day. Given the economic incentive to keep consumers drinking coffee, café owners, restaurateurs, crockery designers and manufacturers ought, presumably, to be interested in anything that can help to enhance the multisensory coffee drinking experience for their clientele cf.
The idea behind experiment 1 came about serendipitously. During a conversation between the first author (GV) and a barista, the latter reported that when coffee is consumed from a white, ceramic mug, it tastes more bitter than when drunk from a clear, glass mug instead; note that these two mug types are amongst the most commonly used vessels to serve coffee in Australian cafés and restaurants. In the present study, we therefore sought to establish the validity of this claim which, to our knowledge, has not been described previously. Indeed, as recently highlighted by Spence and Wan, there is a paucity of research on the psychological impact of the receptacles that we use to drink from.
The notion that the colour of the receptacle/plateware can impact taste/flavour perception might relate to Piqueras-Fiszman et al.’s research putatively showing that colour contrast resulted in a red, strawberry-flavoured mousse presented on a white plate being rated as 10% sweeter and 15% more flavourful than when exactly the same food was presented on a black plate, see for an extension of this work; see for an explicit attempt to evaluate the colour contrast account. While contrast represents one plausible explanation for such results, it is important to note that there are also several other possible mechanisms (e.g., priming) that may explain the influence of product-extrinsic colour on taste/flavour ratings. Taking the principal of colour contrast one stage further, and given the conversation with the barista, it was proposed that brown may be associated with bitterness (or, perhaps, is negatively associated with sweetness). If taste were to be affected crossmodally by colour contrast, then coffee that is tasted from a white coffee mug should be rated as somewhat more bitter than exactly the same coffee when consumed from a transparent mug instead.
It is possible that another contrast mechanism (i.e., simultaneous contrast) might affect the perception of taste . Here, if light, opaque, milky brown coffee were to be associated with bitterness, then a light blue mug/surrounding should intensify the brown of the coffee because blue is brown’s complementary colour . This, in turn, would be expected to elevate ratings of bitterness relative to the same coffee when served in a transparent mug. Some famous examples of the use of simultaneous contrast are Heinz’s™ use of a greenish-blue can to set off the red-orange colour of their beans and sauce and Cadbury’s™ use of purple packaging to enhance the colour of their chocolate.
Based on previous work and anecdotal evidence, we explored the impact of the colour of a receptacle on people’s coffee drinking experience. If extrinsic cues influence a consumer’s experience of coffee, and if taste is affected by contrast effects, coffee tasted/drunk from a white mini mug should be rated as more bitter than from a clear mug instead. Given Piqueras-Fiszman et al.’s and Stewart and Goss’work with strawberry mousse and cheesecake, respectively, we thought that it is possible that the brown-bitter association might be enhanced by colour contrast. However, and with regard to the colour of coffee and the colour of the immediate surroundings against which it is presented, simultaneous contrast might be at work. Specifically, the brown of the coffee may be intensified if the coffee is served from a light blue mug. It should be noted that factors other than contrast effects can influence perception. For example, the cup in which the coffee is served may affect us as a function of our perception of the general properties of the cup (i.e., cheap vs. expensive , flimsy vs. strong). We have attempted to control these potentially confounding variables in the present study. That said, and to borrow from Piqueras-Fiszman et al., if the colour of the mug affects the way in which people perceive the colour of the coffee, and the colour of the coffee affects the perception of flavour, then the colour of the mug (and any contrast effect that it elicits) would be expected to influence the perceived properties of the coffee (e.g., bitterness).
The travel mug type exerted a significant influence on participants’ ratings of the perceived intensity of the café latté, F(2,15) = 4.78, p = .025 (see Figure Bonferroni-corrected post hoc tests revealed that the café latté was rated as significantly more intense (p = .026) when served from the white, ceramic mug than when served from the clear, glass mug. None of the other comparisons reached statistical significance. The mug type failed to exert any influence on participants’ ratings of the other attributes of the café latté (see Table .
Given that ratings associated with the transparent glass mug were not significantly different from those associated with the light blue mug in either experiment, it seems as though simultaneous contrast cannot be used to explain the observed results. However, it is possible that colour contrast influenced the intensity/sweetness of the coffee’s flavour. That said, an alternative mechanism (i.e., sensation transference) might also be at play in experiment 1 In short, implicit judgments regarding the intensity of the white mug may be transferred to the coffee causing it to be perceived as more intense than the coffee served in the other mugs. Given Favre and November’s finding that people report coffee served from a brown container to be too strong (i.e., too intense) and our results from experiment 2, it seems unlikely that (1) people would hold an implicit “intensity” judgement for both white and brown colours and (2) ‘sensation transference’ is the mechanism at work here. Similar to an argument made by Piqueras-Fiszman et al., it seems more plausible to suggest that the white background of the coffee mug may have influenced the perceived brownness of the coffee and that this, in turn, was what influenced the perceived intensity (and sweetness) of the coffee. As we replicate the basic finding that the colour of the mug makes a difference, the correspondence between the visual appearance of the mug and aspects of the flavour suggests that colour contrast mechanisms may be at work here.