Flavour-flavour Learning Research Articles

Efficacy of repeated exposure and flavour–flavour learning as mechanisms to increase preschooler's vegetable intake and acceptance

Dutch children's diets, like the diets of many children in Europe and the US are not balanced, do not contain enough vegetables and have been associated with a high prevalence of childhood obesity. Promoting children's vegetable intake is challenging. We investigated the relative effectiveness of repeated exposure and flavour-flavour learning in increasing vegetable intake and acceptance in preschoolers. During an intervention period of 7 weeks, 39 toddlers (aged 1.5 to 4 years) consumed red beet and parsnip crisps at day-care centres in Wageningen, the Netherlands. Half of the group received red beet crisps with a dip of tomato ketchup (Conditioned [C]) and parsnip with a neutral white sauce (Unconditioned, [UC]), whereas for the other half the order was reversed (red beet [UC], parsnip [C]). Preference and ad libitum consumption of vegetable crisps were measured once before and three times after the intervention over the course of a 6-month follow-up period to assess longer-term effects. Intake increased significantly after the intervention for both vegetables (on average with 8 g; an increase of approximately 300%), and this effect was persistent even 6 months afterwards. The increase was irrespective of crisps being offered with C or UC dip sauce. These results suggest a robust and persistent effect of repeated exposure but no effect of flavour-flavour learning. Offering pure vegetable tastes repeatedly is sufficient to increase intake.

Report of the meeting on Aspartame with National Experts

Report of the meeting on Aspartame with National Experts

Understanding Individual Differences in Acquired Flavour Liking in Humans

The majority of human food likes and dislikes are learned, and there are multiple learning models that explain how flavour liking may be acquired. Two models based on flavour-based learning have attracted considerable attention as potential explanations for acquisition of flavour liking. The first model is based on associations between a novel flavour and an existing liked or disliked flavour (flavour-flavour learning: FFL), and the second is based on associations between the flavour and an effect of ingestion (flavour-consequence learning: FCL). However, experi- mental studies of acquired flavour liking based on these models have had mixed outcomes, with as many studies unable to find changes in liking post-training as there are studies reporting positive findings. This brief review discusses the extent to which the apparent inconsistency in the literature may reflect individual differences in evaluation of the training flavour in FFL or the conse- quence in FCL. The conclusion is that an understanding of individual differences can not only help explain the apparent inconsistency of the flavour-learning literature, but it also suggests how differences in sensitivity to these types of learning may have broader implications for both flavour preference development and the potential for overeating.

Heightened responses to the hedonic qualities of sucrose in olfactory conditioning for women scoring high on the three-factor eating questionnaire disinhibition scale

In flavour?flavour learning (FFL), repeated co-experience of a novel flavour and a hedonically valanced flavour can lead to changes in liking for the novel flavour. Some studies suggest that restrained eaters are insensitive to FFL, while disinhibited eaters may over respond to hedonic stimuli. Here we assessed FFL through associations between food-related odours and sweet and bitter tastes to explore further how eating attitudes influence FFL. 52 women, pre-selected to be high or low on the restraint and disinhibition factors from the Three-Factor Eating Questionnaire (TFEQ), evaluated two novel odours orthonasally before experiencing retronasal pairings of one odour with sucrose and the second with quinine before orthonasal re-evaluation of the odours. At post-training, overall liking increased for the sucrose-paired odour but this effect was greater in women with high scores on the TFEQ disinhibition factor. Liking for the quinine-paired odour decreased equally in all groups. The sucrose-paired odour was rated as sweeter, and quinine-paired odour more bitter at post-training and these acquired sensory qualities were unaffected by restraint or disinhibition factors from the TFEQ. Overall, these data found no evidence of impaired FFL in restrained women, but instead found greater responsiveness to hedonic qualities of sucrose in women scoring high on the disinhibition factor, consistent with suggestions that this factor identifies individuals with heightened hedonic sensitivity to food.

Effects of hunger state on flavour pleasantness conditioning at home: Flavour–nutrient learning vs. flavour–flavour learning

This study examined acquired liking of flavour preferences through flavour-flavour and flavour-nutrient learning under hungry or sated conditions in a naturalistic setting. Each participant consumed one of three versions of a test drink at home either before lunch or after lunch: minimally sweetened ( 3% sucrose, 40 kcal), artificially sweetened (3% sucrose 40 kcal plus artificial sweeteners ASPARTAME) and sucrose-sweetened (SUCROSE: 9.9% sugar, 132 kcal). The test drink was an uncarbonated peach-flavoured iced tea served in visually identical drink cans (330 ml). Participants preselected as "sweet likers" evaluated the minimally sweetened flavoured drink (conditioned stimulus, CS) in the same state (hungry or sated) in which they consumed the test drink at home. Overall, liking for the CS flavour increased in participants who consumed the SUCROSE drink, however, this increase in liking was significantly larger when tested and trained hungry than sated, consistent with a flavour-nutrient model. Overall increases in pleasantness for the CS flavour in participants who consumed the SUCROSE drink when sated or the ASPARTAME drink independent of hunger state, suggest that flavour-flavour learning also occurred. These results are discussed in light of current learning models of flavour preference.

Effects of dietary restraint on flavour-flavour learning

Flavour preference learning in 21 restrained and 21 unrestrained females was explored using an evaluative conditioning paradigm. Each participant was exposed to an adapted version of the procedure used by Johnsrude et al., (1999, Learning & Motivation30, 250–264). During conditioning, participants sampled 10 instances each of three novel flavours presented in a semi-randomized order. After sampling a flavour they were instructed to eat a sweet according to three different flavour-reinforcement contingencies. One flavour was accompanied by a sweet on 90% of trials and was presented alone on 10% of the trials, while the remaining flavours were rewarded at ratios 50%:50% and 10%:90%, respectively. The conditioning phase occurred in conjunction with a counting task requiring continuous use of working memory, and was immediately followed by the participants making hedonic ratings of each flavour. Very few participants showed awareness of the purpose of the experiment or the specific reward contingencies. Despite this, the ratings given by the unrestrained eaters were highly correlated with the reward ratio experienced during conditioning. In contrast, restrained eaters exhibited no evidence for evaluative learning. These findings may explain the equivocal nature of results from previous studies of positive flavour-flavour learning (FFL) and may offer a novel theoretical context within which to study dietary restraint.