Analysis of the US-preexposure effect in flavor acceptance conditioning

In three experiments, rats received exposure to a sucrose solution followed by conditioning with a neutral flavor as the conditioned stimulus (CS) and sucrose as the unconditioned stimulus (US). In Experiments 1 and 2, some rats were given both the preexposure and the conditioning phases in a highly familiar context (the homecage), whereas other animals received both phases in a novel and distinctive context. In both cases the magnitude of the conditioning effect was reduced by preexposure to the US. Experiment 3 directly assessed the possible role of contextual cues by changing the context between the exposure phase and the conditioning phase but found no loss of the US-preexposure effect in these conditions. These results lend no support to the blocking-by-context account of the US-preexposure effect; alternative interpretations are considered.     

The impact of mediodorsal thalamic lesions on olfactory attention and flavor perception

Olfactory attention may be important in generating odor-induced tastes - an arguably universal form of synesthesia - by ensuring that the taste concurrent is captured by the nose and olfaction, not by the mouth and gustation (oral-capture). To examine the role of olfactory attention in generating odor-induced tastes and oral capture we tested a small sample (n = 4) of participants with likely impairments in olfactory attention - individuals with mediodorsal thalamic nucleus (MDNT) lesions. These participants were compared to two sets of controls on tests of olfactory attention, oral capture, odor and flavor perception, and control tasks. MDNT participants demonstrated impaired olfactory attention and enhanced oral capture. Greater oral capture was associated with greater olfactory attentional impairment. These findings imply that olfactory attention may be important in attributing odor-induced tastes to the olfactory modality. However, unlike for visual binding and for the neurodevelopmental synesthesias, where attention may be necessary to demonstrate both phenomena, olfactory attention deficits did not impair flavor binding or the experience of odor-induced tastes.     

Flavor Fatigue: Cognitive Depletion Influences Consumer Enjoyment of Complex Flavors

Surprisingly, little research has examined how consumer responses to specific flavor characteristics of food are formed or how they may fluctuate situationally. We address this lacuna in the literature on the hedonic appreciation of food by demonstrating that enjoyment along one important gustatory dimension, flavor complexity, varies with the degree to which consumers are mentally depleted. Specifically, showing that gustatory sensations are more cognitively demanding than previously thought, findings from three studies evince that cognitive depletion reduces consumer enjoyment of complex‐flavored (but not simple‐flavored) foods via a reduction in pleasure that otherwise can be derived from complex flavors. We establish this effect across three different food categories and provide preliminary evidence for consumers’ ability to identify flavors as the underlying process. Our findings offer theoretical contributions and avenues for future research.     

Extinction, spontaneous recovery and renewal of flavor preferences based on taste-taste learning

This paper presents evidence of extinction, spontaneous recovery and renewal in a conditioned preferences paradigm based on taste-taste associations. More specifically, in three experiments rats exposed to a simultaneous compound of citric acid-saccharin solution showed a preference for the citric solution when the preference was measured with a two-bottle test (citric vs. water). Experiment 1 revealed that conditioned preferences were extinguished by repeated presentations of the citric acid solution without the saccharin. In Experiment 2, an additional test trial was introduced 21 days after the extinction treatment. Delayed testing resulted in the recovery of the extinguished preference for the citric, reflecting a spontaneous recovery effect. Experiment 3 revealed a preference renewal effect that was obtained when the extinction was conducted in a context different from that of the remaining experimental stages. The implications of these results are analyzed with attention paid to the mechanisms underlying learning of flavor preferences.     

Object Concepts in the Chemical Senses

This paper examines the applicability of the object concept to the chemical senses, by evaluating them against a set of criteria for object‐hood. Taste and chemesthesis do not generate objects. Their parts, perceptible from birth, never combine. Orthonasal olfaction (sniffing) presents a strong case for generating objects. Odorants have many parts yet they are perceived as wholes, this process is based on learning, and there is figure‐ground segregation. While flavors are multimodal representations bound together by learning, there is no functional need for flavor objects in the mouth. Rather, food identification occurs prior to ingestion using the eye and nose, with the latter retrieving multimodal flavor objects via sniffing (e.g., sweet smelling caramel). While there are differences in object perception between vision, audition, and orthonasal olfaction, the commonalities suggest that the brain has adopted the same basic solution when faced with extracting meaning from complex stimulus arrays.