The Multisensory Mouth: An investigation into the Motivational, Cognitive and Emotional mechanisms, driving Oral behaviours
This project focuses on the role olfactory and oral perception plays in shaping our consummatory experiences, preferences, and food seeking behaviours. Research into this area is important to health research, shaping understanding of individual differences in food selection, consumption, and other dietary behaviours. It is also informative for food and drink manufacturers who want to understand the factors which drive consumers to select one product over another as well as which measures of consumer experience are the best predictors of product enjoyment and repeat purchasing.
Concepts of motivation provide a framework for investigating the psychological processes by which external stimuli, internal physiological and affective states, and cognitive processes interact to guide real world behaviour. Central to the concept of incentive motivation is hedonic reward, the sensory pleasure derived from consumption of rewarding items. Liking of a reward, such as a food, is a key affective driver of motivated behaviour. Furthermore, through the process of conditioned reinforcement, stimuli associated with the sensory pleasure of consuming a reward also acquire an incentive value and elicit goal-directed approach behaviour or wanting, aimed at obtaining the predicted reward.
Ambient food odours are conditioned stimuli that, through their incentive value, have been reported to prime goal-directed behaviour. However, some studies report that both conscious and non-conscious exposure to ambient odours can instead induce satiety effects, reducing self-reported expected liking and the probability of an associated food being selected for consumption.
Study 1: Wanting (Odours)
The Aim of study 1 was to determine whether exposure to ambient food odours produces a goal priming or a satiety effect and to establish whether any such motivational changes could be detected through an implicit effort-based measure of wanting - thus extending previous use of explicit choice tasks which can be affected by demand characteristics and dietary habits.
Study 2: Wanting (Food Consumption)
The Aim of study 2 was to establish whether, as previously reported, grip force is a reliable measure of wanting by demonstrating that reductions in incentive drive induced by satiety can be detected through subtle implicit changes in effort expended to obtain them.
Individual differences in approach motivation have been widely reported. Individual differences in perceptual processing are also known to affect the detection, salience and ultimately behaviour elicited by sensory cues in our environment. In the real world, ambient odours are rarely encountered in isolation, thus the brain must segregate motivationally relevant odour objects, typically comprised of 10s – 100s of individual volatiles, from the complex olfactory background they are encountered against. While the cognitive basis of olfactory scene analysis has received little attention to date, state and trait differences in the processing of visual scenes is well documented.
Study 3: Individual Differences
The Aim of study 3 was to determine whether a local processing advantage in the visual domain is associated with superior ability to dis-embed component odour objects from within a multicomponent mixture. Such findings give insight into the domain general and domain specific cognitive processes underlying olfactory processing.
Oral processing of food stuffs is a multisensory process where gustatory, olfactory and somatosensory cues combine to generate a unitary percept termed flavour. Individual differences in affective responses to flavours are widely reported and are affected by cultural, personality and other demographic factors. Genetic Taster Status, an inherited relative sensitivity to taste stimuli, reflecting individual variation the density of fungiform papillae on the tongue, is predicted to impact not just sensitivity to tastants but also to the somatosensory and chemesthetic properties of oral stimuli. However, to date studies are limited and findings mixed.
Study 4: Liking
The Aim of study 4 was to determine whether facial EMG, an established measure of affective responses to sensory stimuli, can be used to differentiate between PROP tasters and non-tasters in their affective responses to threshold and suprathreshold bitter, astringent and chemesthetic compounds. Such an implicit measure of immediate liking has advantages over traditional ratings scales which are vulnerable to demand characteristics and require interruption of the hedonic response for completion.
Who is carrying out the study?
This PhD is funded by Glaxo-Smith Kline and the BBSRC. All research will be carried out in the labs at Liverpool John Moores University.
Study 3 is currently still running and looking to recruit females aged 18-40, If you are interested in taking part, please contact the Principal Investigator to request a Participant Information Sheet.