Effects of exposure on taste preference development in infancy

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EFFECTS OF EXPOSURE ON TASTE PREFERENCE DEVELOPMENT

IN INFANCY

Rebecca Johnson and Gillian Harris School of Psychology, University of Birmingham, Edgbaston, Birmingham B15 2’IT England. Studies with animals and humans have shown that exposure to a food (assuming that the exposure is not followed by negative consequences) will enhance the preference of that food. The absence of any aversive consequences positively reinforces the associated flavour of the ‘safe’ food and neophobia is dissipated. It has been suggested that there is a developmental window at around 3-4 months-old when there is a period of optimal acceptance for new tastes/minimal neophobia (Harris, 1993). During this period exposure effects on food preference may be greater than any other time of life. If infancy is indeed the optimal period for introducing new tastes, exposure may enable tastes which are typically rejected (sour and bitter) to be accepted. In a study designed to measure the effects of exposure on liking for the tastants sweet, salt , sour and bitter, infants were fed different flavours of baby rice. The infants were tested as soon after weaning as possible. The first stage of testing was carried out over five consecutive days. Each infant was randomly assigned to a ‘target taste’ (either sweet, salt, sour or bitter) and a ‘baseline taste’ (this was any taste other than the target taste). Using an ABBAC/BAABC design the infant was presented each day with either plain baby rice (A) or baby rice containing the target taste (B). On the final day, baby rice containing the baseline taste (C) was given. The mother was asked to feed the baby rice until specific refusal criteria were met. Preference was measured by weighing the amount of rice that has been consumed. All the feeding sessions were video-taped to check that the refusal criteria were followed and infant signals of satiety were not ignored. Following the five days of testing mothers were given 15 samples of rice containing the target taste. The mothers were asked to feed the rice to their baby every day and told that the amount the child ate was not important as long as the child tasted it on each occasion. After 15 days the second stage of testing was carried out using the same ABBAWBAABC procedure that was used for the first stage of the testing. This procedure enables comparison between intake after 15 taste exposures (B) and intake without the exposure (C) relative to intake of plain rice (A). Significantly higher intake after exposure compared to no exposure will provide evidence that exposure effects occur in infancy. If this is found for sour and bitter tastes this will indicate that exposure effects are particularly salient during infancy. Data collection is currently underway. Preliminary analysis suggest that exposure increases liking for sour and salt tastes. Subsequent data collection and analysis will confirm the significance of these results, and show the effects of exposure on sweet and bitter tastes.

Reference Harris, G. (1993) Introducing the Infant’s First Solid Food. British Food Journal 95:7-10.