le même processus pour tous - Université de Bourgogne

Chem. Percept.
Fig. 6 Four-dimensional
compromise maps of the products
with 95% confidence ellipsoids
computed by bootstrap on
trained assessors and the two
groups of untrained assessors'
data. The solid black lines represent
the dark beers, the dashed
gray lines represent the amber
beers, and the dotted gray lines
represent the blond beers
0.05]. This shows that trained assessors were more
consensual than untrained assessors on their categorization.
Discussion
With this experiment, we wanted to explore what
categorization criteria are used by trained and untrained
beer assessors when they organize their perceptions of
beers. We used sorting tasks in order to study two
different criteria, beer color and brewery, in two tasting
conditions, visual and blind conditions. We expected that
the organization of beer perceptual spaces would be
different for trained and untrained assessors because
trained assessors have knowledge about beer sensory
characteristics that could affect their categorization
criteria.
Influence of Visual Information on Beer Categorization
In the visual condition, trained and untrained assessors both
clearly categorized beers by color, whereas in the blind
condition, they categorized beers by brewery. This result
suggests that in a beer categorization task, both trained and
untrained assessors tend to rely more on visual information
than on chemosensory information. While this visual
dominance is not surprising for untrained assessors, we
expected trained assessors to be less influenced by beer
color because they are used to taste beer under red light and
to focus their attention on beer taste and aroma. Moreover,
the trained assessors declared that they had not based their
sort on visual information but on beer chemosensory
properties. Yet, such an influence of color on taste experts'
chemosensory perception has been previously reported. For
example, Pangborn et al. (1963) found an effect of color on
the sweetness perception of wines: a white wine colored
pink (in order to give it the appearance of a blush wine) was
perceived by wine experts as sweeter than the same
uncolored wine. More recently, Morot et al. (2001) showed
that wine experts described the odor of a white wine
artificially colored in red as a red wine. The results of the
experiment of Morrot et al. demonstrate that experts rely on
visual appearance for interpreting chemosensory information.
In other words, humans are so visually oriented that
even experts look for visual cues when they interpret
chemosensory information, and these visual cues may mask
other information as we observed here. This masking
phenomenon can be explained either in terms of selective
attention or in terms of congruence seeking. From a
selective attention perspective, we can hypothesize that
assessors could not process both visual and chemosensory
information at the same time and that they performed the
categorization task mostly on visual information, tuning out
smell, and taste information. From a congruence-seeking
perspective, we can hypothesize that assessors can switch
their attention from visual information to chemosensory
information but that chemosensory perception is driven by
visual information. That is, when attending to chemosensory
information, assessors will, unconsciously, seek a
confirmation of visual information rather than analyzing
smell and taste properties. This second explanation might
Fig. 7 Means and standard errors of R V coefficients computed
between the individual matrices of each assessor and the rest of her/
his group for trained and untrained assessors for the first repetition