YOUR SENSE OF THE WORLD AND MOVEMENT WITHIN IT
The most salient thing about smells is probably whether they are
pleasant, disgusting, or somewhere in-between. It used to be thought
that much of this emotional reaction was acquired throughout our lives,
based on association and cultural connotations. However, a surprising
study published in 2009 suggests many of our preferences for smells
may be hard-wired, and that they can be predicted by those smells that
are liked by mice!
Nathalie Mandairon asked thirty participants to rate their preference
for a range of odours including geraniol, which has a floral smell, and
guaiacol, which has a smoky whiff about it. The researchers were careful
to use smells that weren’t biologically significant – for example, signal-
ling danger or rotten food. Despite the apparently random nature of
the odours, the ones the participants said they favoured, such as gera-
niol, tended to be the same as those that thirty mice spent the longest
time sniffing. Similarly, the odours that the humans liked least, such as
guaiacol, tended to be the ones the mice were least interested in. The
researchers weren’t sure what distinguishes a preferred smell from a
disliked one, but the difference must reside ultimately in the chemical
structure of the substances, and this experiment suggests we are born to
prefer some over others.
Ta s t e
Related to smell is our sense of taste. The flavour of food comes from
these two senses being combined, which is why food doesn’t seem as
enjoyable when you’ve got a cold and your nose is blocked. The percep-
tion of taste arises from receptors located on your tongue, particularly
along the edges. Scientists usually talk about there being four “primary
tastes”: sweet, sour, salty and bitter. A possible fourth is “umami” which is
triggered by monosodium glutamate, a chemical that’s commonly used
in snack foods. Compared with vision, we have few words for describing
flavours. Without actually mentioning the food you’re eating, have a go
at describing the taste of your latest meal to a friend and you’ll see what
I mean. Many of us even get confused between two of the main taste
categories of sour and bitter – the first being like a lemon and the second
like tonic water or onion juice.
From a psychologist’s perspective, one of the most interesting things
about taste is just how susceptible it is to suggestion and expectation.
For example, Jack Nitschke and his collaborators at the University of
Wisconsin trained students to associate a range of flavoured water-