Foraging minds in modern food environments : A high-calorie bias in human spatial memory and its implications for eating behavior

The modern food environment is characterized by an overabundance of energy dense foods, stimulating the (over)consumption of ‘unhealthy’ high-calorie items. However, not everyone overeats, indicating that large differences exist in how individuals respond to the heightened systemic availability and accessibility of high-calorie foods. This thesis is grounded on the novel premise that differences in the ability to successfully navigate current “obesogenic” settings may (partially) stem from a cognitive adaptation that evolved for optimal foraging within harsh ancestral food environments. Specifically, from the graded expression of a calorie-sensitive cognitive system that enabled ancestral humans to efficiently (re)locate valuable nutritional resources with varying spatiotemporal availabilities – a bias in spatial memory for high-calorie foods. To this end, we empirically examined the existence (i.e. expression) of a potential inbuilt prioritization or “bias” in human spatial memory for high calorie foods, as well as its implications (i.e. translation) for individual eating behavior within a modern food environment.In Chapter 2, we investigated whether food-specific biases in human spatial memory are expressed, across sensory modalities (i.e. vision and olfaction) of ecological significance to foraging. We report on two controlled lab experiments featuring a computer-based spatial memory task with food images (Study 1; N = 88) and food odors (Study 2; N = 88), respectively. We also probed associations between food-specific biases in spatial memory and a range of (incidental and routine) eating-related parameters. We found that individuals more accurately recalled the locations of high-calorie and savory-tasting foods, while controlling for consciously mediated valuations or personal experiences with foods. However, effects of biases in food spatial memory were not present on eating-related parameters.Chapter 3 describes an ambitious test for the existence of the high-calorie spatial memory bias outside of “sanitized” lab settings. We carried out a large (N = 512) multisensory field-based experiment that allowed for two additional noteworthy elements: spatial navigation between distinct (three-dimensional) positions of food stimuli, and the incidental encoding of food locations. This format similarly enabled us to compare food spatial memory performance (and corresponding biases) between different sensory environments (i.e. multisensory condition (N = 258) versus olfactory (N = 254) condition). We found that individuals incidentally learned and more accurately recalled locations of high-calorie foods – regardless of explicit hedonic valuations or personal familiarity with foods. In addition, the high-calorie spatial memory bias was equally expressed in both sensory environments – even where solely odor information was available.Chapter 4 utilized a real-world food environment to assess the behavioral translation of the high-calorie spatial memory bias. In a lab-plus-field experiment, we investigated the bias’ effects on the food search and food choice of 60 individuals navigating an unfamiliar supermarket. Across two test sessions, participants performed eye-tracking and spatial memory tasks in a lab setting, and then completed food search and (covert) food choice tasks in a supermarket. Although individuals were faster at localizing high-calorie versus low-calorie foods in the supermarket, the high-calorie spatial memory bias did not predict a lower search time for high-calorie foods, or a higher proportion of high-calorie food choice. Rather, an enhanced memory for high-calorie food locations was associated with a lower perceived difficulty (i.e. greater ease) of finding high-calorie items in the supermarket, which may potentiate later choice of a high-calorie food. The expression of the high-calorie bias in spatial memory was also not associated with a bias in attention for high-calorie foods.In Chapter 5, our focus was on implications of the high-calorie spatial memory bias for individuals’ routine (repeated) eating behavior. In an online study, we tested the food spatial memory of a diverse sample of 405 individuals, as well as examined associations between the high-calorie spatial memory bias and the routine frequency of high-calorie snack consumption, exposure to high-calorie food environments, and BMI of a subset of 316 individuals. We also assessed individual psychological factors (e.g. snack purchasing habits, inhibitory control) that could either synergize or antagonize the bias’ behavioral effects. A greater expression of the high-calorie spatial memory bias predicted a stronger habit of purchasing high-calorie snack foods and consequently a higher individual BMI. Although individuals from various sociodemographic groups expressed the high-calorie bias in spatial memory, our results demonstrate that those with a better inhibitory control to high-calorie foods were protected from bias-induced tendencies to frequent high-calorie food outlets.Chapter 6 questions whether the high-calorie bias in spatial memory can be reasonably generalized to individuals from varying cultures. Through the means of a cross-cultural online experiment (and data from Chapter 5), we compared the food spatial memory of diverse populations from the USA (N = 72), Japan (N = 74), and the Netherlands (N = 405) using a standardized computer-based spatial memory task. We demonstrate that individuals native to cultures that diverge on relevant cognitive characteristics, built food environments, and food attitudes were effectively identical in their food relocation performance: Locations of resources with a higher caloric quality were more accurately recalled than that of low-calorie alternatives to a similar degree across countries, regardless of individuals’ hedonic preferences and familiarity with foods, or explicit effort to encode food locations. The high-calorie bias in spatial memory was also uniformly expressed by diverse sociodemographic groups within a population.In conclusion, this thesis provides compelling evidence for an inbuilt prioritization of  high-calorie food locations in human memory. Importantly, this high-calorie bias in human spatial memory maladaptively influences how we navigate the modern food environment, by increasing the perceived ease of locating high-calorie foods, habitual high-calorie snack food purchases, visits to high-calorie food outlets, and individual BMI. Though diverse populations were all shown to express the spatial processing bias, individuals with a better ability to inhibit responding to high-calorie foods were protected from the bias’ translation into undesirable dietary outcomes. In closing, human minds seem to be adapted for the efficient location and consumption of high-calorie foods within the harsh ancestral food environments in which we evolved. Fine-tuning ways to mitigate unwanted tendencies of our “foraging minds” would bring us a step closer to promoting healthier eating behavior within our evolutionary-novel calorie-abundant food landscape.