Elsevier

Appetite

Volume 51, Issue 2, September 2008, Pages 273-282
Appetite

Research report
Food memory and its relation with age and liking: An incidental learning experiment with children, young and elderly people

https://doi.org/10.1016/j.appet.2008.02.019Get rights and content

Abstract

The present study compared incidental learning and food memory in children, young adults and elderly people for three sensory modalities (taste, texture and aroma). The relation of gender and liker-status (i.e. how much we like a product) with food memory was also investigated. Participants received a complete meal including a custard dessert used as target under incidental learning conditions. 24 h later, participants were confronted with a series of samples consisting of the target and slightly modified versions of the target (distractors) and were unexpectedly asked to perform an “absolute memory” (“Did you eat this sample yesterday?”) and a “relative memory” test (“Is the present sample less/equal/more pleasant than the one you ate yesterday?”). Participants also performed a hedonic and a discrimination test. Memory for the custard was poor and did not depend on age, but it was related to gender, and to how much participants liked the product. Females and high-likers outperformed males and low-likers in the absolute memory task, but they were not better in discriminating the products on both the hedonic and the perceptual dimension. Results also showed that, contrary to common belief, not all sensory aspects that can be discriminated in perception and in liking, are equally well remembered.

Introduction

Memory is omnipresent in our life. All our actions are regulated and influenced by memory, which constantly provides information necessary to manage and resolve the tasks of our everyday life. However, we are not often aware of using our memory. When eating a pizza or drinking coffee during breakfast, it is extremely unusual to consciously decide “I have to remember this food” (Issanchou, Valentin, Sulmont, Degel, & Köster, 2002). Actually, much of our knowledge about food is acquired incidentally, without any explicit attention or learning, and stored implicitly (Mojet & Köster, 2005). As a consequence it guides our food choice and food intake.

Although the implicit nature of food memory is evident, most of the studies available on memory of sensory stimuli deal with conscious and intentional mechanisms of learning, thus omitting the incidental component of such processes and the understanding of food memory under ecological conditions (Issanchou et al., 2002).

Only recently, Mojet and Köster (2002) proposed and validated an incidental learning paradigm to study the properties of food memory in a natural, ecological condition. The experiment consisted of inviting people to have a meal under the false pretence of studying their hunger feelings. Participants were offered a standard meal containing a number of target items and were asked to rate their hunger feeling over the day. To ensure incidental learning of the target items, memory was never mentioned. When the participants came back to the laboratory, they were unexpectedly asked to perform a memory test. They were confronted with a series of samples consisting of the target and slightly modified versions of the target (distractors), and for each sample they had to indicate whether this sample had been eaten during the previous meal or not. In their first paper on texture memory, Mojet and Köster (2002) showed that there was a memory for texture alone, although memory was improved when an involuntary contribution of flavour could not be avoided. The same paradigm was also applied to investigate memory for taste (Köster, Prescott, & Köster, 2004), texture (Mojet & Köster, 2005) and flavour (Møller, Mojet, & Köster, 2007). Köster et al. (2004), exploring food memory in orange juice (modified in sweetness and bitterness), yoghurt (modified in sweetness and sourness) and cream cheese (modified in sourness and bitterness), found that incidental learning of taste occurred, but not to the same degree for the different tastes (i.e. sourness and bitterness were better remembered than sweetness) and that memory was partly product dependent. Mojet and Köster (2005), testing memory for texture in solid (biscuit), semi-solid (yoghurt) and liquid (breakfast drink) food varied in fattiness, crispiness and thickness, found that memory was poor for fattiness, but good for thickness and crispiness.

Very recently, the present authors used a multi-sensory approach to investigate the relative importance of taste, texture and aroma in the incidentally learned memory for a food (Morin-Audebrand et al., 2007). In that experiment, the three sensory modalities were each independently varied in the same food (i.e. a vanilla custard dessert). Results showed that taste was better remembered than aroma, which was only marginally remembered and that in this case no memory for texture was found.

The studies mentioned above reported results predominantly obtained with adults without taking in consideration the possible influence of age on food memory. It is largely believed that memory declines with age, but only few studies investigated whether this decline concerns sensory memory too. Larsson (1997) reported that the decline in elderly people's memory is especially prominent in episodic memory which requires conscious recollection of personally experienced events acquired in a particular place at a particular time. Møller, Wulff, and Köster (2004), studying incidental and intentional memory for uncommon odours, showed that memory based on incidental learning was as good in the elderly as in young adults, but that with intentional learning, the memory of the young adults was better than that of the elderly. Very recently, Møller et al. (2007) compared memory performance of a group of young adults and of elderly people under both intentional and unintentional (incidental) learning conditions using real products (i.e. two different types of soups). As in the previously mentioned studies, the authors showed that when not explicitly asked to remember the sensory aspects of the food, the elderly performed as well and even slightly better than the young adults, but that under an intentional learning condition the young adults tended to be better.

Very little is known about food memory in children. The few studies presented in the literature were carried out on infants and dealt with prenatal and early postnatal exposure to odours and flavours. For instance, Schaal, Marlier, and Soussignan (2000) showed that odour learning occurred in foetuses within the amnion and that this information persisted at least over the first 4 postnatal days. Accordingly, Mennella, Jagnow, and Beauchamp (2001) found that prenatal flavour experiences influence postnatal responses to that flavour in solid foods.

So far, no studies have compared food memory in children, young adults and elderly people. In the present study, food memory in these three age groups was assessed under incidental learning conditions using the implicit paradigm developed by Mojet and Köster (2002). Memory was tested for three sensory modalities (i.e. taste, texture and aroma) that were each independently varied in concentration in the same food product. Both “absolute memory” (recognising the target amidst the distractors) and “relative memory” for liking (judging whether the stimuli presented in the second day session were less, equally or more liked than the one eaten previously) were investigated. Although already covered in an earlier paper (Morin-Audebrand et al., 2007), the results of the young adults on absolute and relative memory for liking are represented here again to be compared with the results of the children and the older participants. Furthermore, in contrast to that earlier paper, the present paper devotes particular attention to the relation between memory and the discrimination capacity as shown in both a perceptual and a hedonic test.

The main aim of this paper is to establish the relation between age, gender and liking and incidental learning and memory for food. The relative importance of the three sensory modalities of interest (taste, texture and aroma) on food memory is extensively described in another paper (Morin-Audebrand et al., 2007).

Section snippets

Participants

One-hundred-twenty-six participants took part in the study: 42 children (18 males and 24 females; mean age 10.0 ± 0.8 years, range 9–11 years), 43 young adults (19 males and 24 females; mean age 26.7 ± 6.8 years, range 18–41 years) and 41 elderly people (18 males and 23 females; mean age 68.7 ± 5.7 years, range 60–83 years). Participants were selected on the basis of a food preference questionnaire (for the children, this questionnaire was completed by the parents). Only participants who liked

Absolute memory

The recognition index, calculated over all participants, was not significantly different from zero, indicating that, in general, memory performance was poor. No overall age effect was found for the recognition index, but when splitting the participants according to age, the recognition indices of the children and the elderly were not significantly different from zero, whereas the recognition index of the young adults tended to be higher (M = 0.08; t(42) = 2.05; p < 0.10).

A significant overall gender

Discussion

The main outcome of this study indicates that, in general, the ability to remember a previously encountered food is poor and bears no relation with age, but it is related to gender and to how much the participants like such a food. The finding that incidental learning of food does not deteriorate with age is in agreement with other studies in which the ability to remember food products has been tested in a control group of young adults compared to a group of elderly people in both intentional

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