Certain interoceptive hunger cues are caused by gut physiology. These interoceptive cues may have psychological consequences, namely an ability to enhance the desire to eat, which are independent of their physiological cause. Testing this idea is difficult because the physiological processes are normally linked to any consequence. In this preliminary report we attempted to induce an interoceptive hunger cue (a stomach rumble), to examine its psychological consequences independent from its physiological cause. In three online Studies (1-3), participants viewed images of food while listening to different sounds including quiet stomach rumbles and judged the source of the sound, and their desire to eat the depicted foods. In Studies 1-3, irrespective of when they last ate and their reported level of hunger, and relative to control sounds, stomach rumble sounds enhanced desire to eat depicted foods, especially when they were mislocalised to the participants’ own stomachs. In Study 1 49% of participants reported some degree of mislocalisation, 74% in Study 2, and 77% in Study 3. Overall, around 40% reported mimicry, where they felt that hearing the computer-generated stomach rumble sound induced the same in themselves. In Study 3 heart beat sounds were included. These too were mislocalised, and enhanced desire to eat depicted foods. In sum, this preliminary report suggests it may be possible to psychologically induce interoceptive cues, including one specific to hunger, and that these cues may then enhance food desire when mislocalised to self. In addition, the findings support the idea that interoceptive hunger cues may have associative properties that augment desire to eat.

Internal bodily sensations such as an empty rumbling stomach can lead to enhanced desire for food - hunger. As an empty rumbling stomach is caused by digestive physiology, it is often presumed that such physiological processes also cause hunger. However, psychological processes could equally generate hunger (e.g., based on what the physiological signal has come to connote), and here we outline a method to test this idea. Participants were exposed to a stomach rumbling sound and control conditions (machine sound and silence) while they viewed pictures of food and everyday objects. For each picture, participants evaluated their desire to consume or own it, and judged, if there was a sound, where they felt it came from. Over half the participants experienced an illusion in which they mis-localised the stomach rumble sound to their own body. These participants also judged the pictures of food to be more desirable than comparable food pictures in the control conditions. This effect was obtained irrespective of when they had last eaten. Relative to control conditions, the stomach rumble sound had little impact on desire for pictures of everyday objects. These findings suggest it is possible to generate an illusory interoceptive state independent of physiology, which can then enhance desire to eat. This implies that purely psychological processes can generate bodily-cued desires.

Globally, fruit and vegetable (F&V) consumption is lower than recommended, with inadequate consumption linked to many non-communicable diseases. Inadequate F&V consumption can, in part, result from the cost and access barriers to fresh F&V that are present in certain parts of the world. While use of canned and frozen F&Vs may provide a solution, their consumption/acceptability tends to be lower than fresh F&V. This study explored the explicit and implicit biases that may exist towards canned and frozen F&V in comparison to fresh equivalents. In Study 1, participants were administered self-report scales that measured their beliefs towards canned, frozen and fresh F&V across health, convenience, and appeal, including the impact of Australia's health star rating system. In Study 2, Implicit Association Tests were administered for canned and frozen F&V, versus fresh. In Study 1, explicit ratings confirmed a strong preference for fresh F&V, particularly regarding health, even when participants were informed about the equivalent health star ratings. The study also highlighted a convenience advantage for canned and frozen foods, although these benefits did not outweigh the bias towards fresh produce. In Study 2, an implicit bias against canned and frozen F&V was evident, with significantly slower categorization times for positive associations, compared to fresh F&V. These findings indicate the existence of an attitudinal bias against frozen and canned F&V. To increase intake of F&V, especially when fresh F&V is not accessible/ affordable, future research needs to understand how to target the identified biases that limit consumption of canned and frozen alternatives.

People match gustatory (basic tastes) and non-gustatory stimuli (e.g., colors, shapes, and textures) to each other in a reliable manner. Yet, whether other attributes of the experience of flavor, such as, for example, astringency also evidence such reliable crossmodal mappings is currently unknown. Therefore, the aim of this study was to assess whether individuals make reliable crossmodal mappings between astringent solutions and non-gustatory stimuli (e.g., colors, shapes, hand-felt roughness/smoothness), and to examine the basis of any mappings observed. Participants sampled 6 solutions - astringent and 5 basic tastants - at 2 concentrations each (low, high), and for each selected their best matching color, texture, and shape (in three separate counterbalanced blocks). After making their selections, the participants evaluated the valence of the solutions, their colors, textures, and shapes, as well as the qualities/intensities of the solutions, and their confidence in the matches they made. Participants reported the rationale for their color-, texture- and shape matches at the end of the study. Color, texture, and shape selections evidenced consensual mappings, and participants were generally confident in all matches to a comparable level. Whilst people typically reported that their color matches were driven by real world associations (e.g., yellow chosen for sour, as lemons are yellow and sour), followed by valence (liking; e.g., pink for sweet, as both are liked), texture and shape matches to solutions were more attributable to intensity (e. g., rougher textures, selected for rougher feeling [e.g., astringent] solutions) as well as valence. Implications for flavor binding and marketing are discussed.

People can use their internal state to determine if they are hungry or thirsty. Although the meaning of some interoceptive cues may be innate (e.g., pain), it is possible that others-including those for hunger and thirst-are acquired. There has been little exploration of this idea in humans. Consequently, we conducted a survey among child caregivers to determine if the basic conditions necessary for interoceptive learning were present. Two-hundred and thirty-five caregivers of children aged 1-12 years were asked if they had recently noticed stomach rumbling, hunger-related irritability, and a dry mouth in their child. They were also asked how they would respond. The impact of several moderating variables, especially caregiver beliefs about the causes of hunger, fullness, and thirst, was also explored. Fifteen percent of caregivers had recently noticed stomach rumbling in their child, 28% hunger-related irritability, and 14% a dry mouth. Forty-four percent of caregivers had noticed at least one of these three cues. Noticing hunger cues was significantly moderated by caregiver beliefs about their cause, by child age, and in one case by temporal context (around vs. outside mealtimes). Key caregiver responses were providing the need (e.g., offer food) and/or asking the child if they had a need (e.g., hungry?). Each type of response could potentially support a different form of interoceptive learning. In conclusion, we suggest the necessary conditions for children to learn interoceptive hunger and thirst cues, are present in many caregiver-offspring dyads.

Hunger refers to (1) the meaning of certain bodily sensations; (2) a mental state of anticipation that food will be good to eat; and (3) an organizing principal, which prioritizes feeding. Definitions (1) and (2) are the focus here, as (3) can be considered their consequent. Definition (1) has been linked to energy-depletion models of hunger, but these are no longer thought viable. Definition (2) has been linked to learning and memory (L&M) models of hunger, but these apply just to palatable foods. Nonetheless, L&M probably forms the basis for hunger generally, as damage to declarative memory can eradicate the experience of hunger. Currently, there is no general L&M model of hunger, little understanding of how physiology intersects with a L&M approach, and no understanding of how Definitions (1) and (2) are related. We present a new L&M model of human hunger. People learn associations between internal (e.g., tummy rumbles) and external cues (e.g., brand names) and food. These associations can be to specific foods (episodic memories) or food-related categories (semantic memories). When a cue is encountered, it may lead to food-related memory retrieval. If retrieval occurs, the memory's affective content allows one to know if food will be good to eat now-hunger-a cognitive operation learned in childhood. These memory processes are acutely inhibited during satiety, and chronically by multiple biological parameters, allowing physiology to modulate hunger. Implications are considered for the process of making hunger judgments, thirst, the cephalic phase response, and motivational and lay theories of hunger.

The psychological states of hunger and satiety play an important role in regulating human food intake. Several lines of evidence suggest that these states rely upon declarative learning and memory processes, which are based primarily in the medial temporal lobes (MTL). The MTL, and particularly the hippocampus, is unusual in that it is especially vulnerable to insult. Consequently, we examine here the impact on hunger and satiety of conditions that: (1) are central to ingestive behaviour and where there is evidence of MTL pathology (i.e., habitual consumption of a Western-style diet, obesity, and anorexia nervosa); and (2) where there is overwhelming evidence of MTL pathology, but where ingestive behaviour is not thought central (i.e., temporal lobe epilepsy and post-traumatic stress disorder). While for some of these conditions the evidence base is currently limited, the general conclusion is that MTL impairment is linked, sometimes strongly, to dysfunctional hunger and satiety. This focus on the MTL, and declarative learning and memory processes, has implications for the development of alternative treatment approaches for the regulation of appetite.

Abstract Biophobia refers to a fear of living things, which leads to alienation from nature. The literature examining the underlying mechanisms and treatment of biophobia is sparse. This review aims to increase the readers' understanding of biophobia by examining the more extensive literature on specific phobias, namely animal phobia, as it most closely resembles biophobia. Fear, anxiety and disgust play an important role in specific phobias. Their triggers and functions are reviewed in the context of animal phobia. Theoretical models for specific phobias suggest that phobias develop because genetically linked behavioural patterns interact with normal development fears and environmental factors. Phobias are then maintained by cognitive and behavioural mechanisms. Exposure therapy, the gold standard treatment for specific phobia, functions to override the maladaptive stimulus–stimulus and stimulus‐response associations responsible for animal and other specific phobias. Its delivery and efficacy are reviewed. We recommend that readers interested in biophobia use the existing knowledge on animal phobia and specific phobia in general to treat biophobia and generate research hypotheses for future study. Read the free Plain Language Summary for this article on the Journal blog.

Disgust serves to defend the body from the entry of toxins and disease. Central to this function is a strong relationship with the proximate senses of smell, taste, and touch. Theory suggests that distinct and reflexive facial movements should be evoked by gustatory and olfactory disgusts, serving to impede bodily entry. While this hypothesis has received some support from facial recognition studies, whether smell and taste disgusts actually produce distinct facial responses, is unknown. Moreover, there has been no assessment of the facial response evoked by contact with disgusting objects. To address these issues, this study compared facial responses to touch, smell, and taste disgusts. Sixty-four participants were asked to touch, smell, and taste disgust-evoking and neutral control stimuli, and rate them on disgust, on two occasions-first, while they were video recorded and second, with facial electromyography (EMG) applied (measuring levator labii and corrugator supercilii activity). Videos were coded for facial expressions by humans and for facial action units (FAUs) by machines. Self-report data confirmed the disgust stimuli as highly disgusting. Comparison of the overall pattern of FAUs evoked by touch, smell, and taste disgusts, indicated two distinct facial disgusts for the proximate senses-a chemosensory and a tactile-disgust face. The nose wrinkle and upper lip raise were central to all facial disgusts, indicating their centrality to the disgust face. Several facial disgusts appear to exist, each with different functional goals.

The hippocampus is a critical brain substrate for learning and memory; events that harm the hippocampus can seriously impair mental and behavioral functioning. Hippocampal pathophysiologies have been identified as potential causes and effects of a remarkably diverse array of medical diseases, psychological disorders, and environmental sources of damage. It may be that the hippocampus is more vulnerable than other brain areas to insults that are related to these conditions. One purpose of this review is to assess the vulnerability of the hippocampus to the most prevalent types of insults in multiple biomedical domains (i.e., neuroactive pathogens, neurotoxins, neurological conditions, trauma, aging, neurodegenerative disease, acquired brain injury, mental health conditions, endocrine disorders, developmental disabilities, nutrition) and to evaluate whether these insults affect the hippocampus first and more prominently compared to other brain loci. A second purpose is to consider the role of hippocampal blood–brain barrier (BBB) breakdown in either causing or worsening the harmful effects of each insult. Recent research suggests that the hippocampal BBB is more fragile compared to other brain areas and may also be more prone to the disruption of the transport mechanisms that act to maintain the internal milieu. Moreover, a compromised BBB could be a factor that is common to many different types of insults. Our analysis indicates that the hippocampus is more vulnerable to insults compared to other parts of the brain, and that developing interventions that protect the hippocampal BBB may help to prevent or ameliorate the harmful effects of many insults on memory and cognition.

Trypophobia is a relatively common aversion to clusters of holes. There is no consensus yet on which emotions are involved in Trypophobia nor in its functional utility. This report investigates the role of disgust using contamination tasks in two studies, which contrast people with an aversion to trypophobic stimuli to those without. In Study 1, participants reported their emotional reactions to imagined contamination of trypophobic images. In Study 2, participants evaluated physically present trypophobic, disgust, fear, and control stimuli. The capacity of these stimuli to contaminate other objects was established using a chain of contagion task. Across both studies, contamination was present, however, only those with an aversion to trypophobic stimuli evidenced contamination on the chain of contagion task, a hallmark of disgust responding. Elevated levels were not only reported for disgust, but also alongside fear/anxiety. Participant reports suggest an underlying disease avoidance mechanism in Trypophobia, with trypophobic participants demonstrating an exaggerated response to such stimuli involving disgust and fear/anxiety, which is also seen in small animal phobia, BII, and C-OCD. Implications, particularly for treatment are discussed.

One prediction derived from the disease avoidance account of disgust is that proximal disgust cues (smells, tastes and touches) should elicit this emotion more intensely than distal disgust cues (sights and sounds). If correct, then memories of disgusting experiences should involve smelling, tasting or touching to a greater degree than seeing or hearing. Two surveys were conducted on university students to test this idea, drawing upon their naturalistic experiences. Survey 1 ( N = 127) asked participants to detail their most memorable disgusting, fear-provoking, morally repulsive and yucky/gross experience, with each recollection self-rated for sensory involvement. Survey 2 ( N = 89) employed the same task, but this time, participants recollected their most common disgusting, fear-provoking, morally repulsive and yucky/gross experience in the preceding week. The majority of disgusting experiences were core disgusts—i.e. related to disease/pathogen presence or stimuli. The proximal and distal sensory cues contributed equally to individuals’ most memorable core disgust experiences, but the proximal senses were more involved than the distal senses in individuals’ most common core disgust experiences. Further, the proximal sensory cues, as compared with the distal sensory cues, were signficantly more involved in core disgust experiences than in morally repulsive and fear-provoking experiences. The implications of these findings for a disease avoidance account of disgust, for multi-sensory disgust research, and core disgust’s classification as an emotion or a drive, are discussed.

The emotion of disgust in humans is widely considered to represent a continuation of the disease-avoidance behavior ubiquitous in animals. The extent to which analogs of human disgust are evident in nonhuman animals, however, remains unclear. The scant research explicitly investigating disgust in animals has predominantly focused on great apes and suggests that disgust might be present in a highly muted form. In this review, we outline the main approaches to disgust. We then briefly discuss disease-avoidance behavior in nonhuman animals, proposing a set of criteria against which evidence for the presence or absence of disgust in animals can be evaluated. The resultant decision tree takes into account other plausible causes of avoidance and aversion when evaluating whether it is likely that the behavior represents disgust. We apply this decision tree to evaluate evidence of disgust-like behavior (e.g., avoidance of carrion and avoidance of feces-contaminated food) in several examples, including nonhuman great apes. Finally, we consider the large disparity between disgust in humans compared to muted disgust in other great apes, examining the possibility that heightened disgust in humans is a relatively recent cultural acquisition.

Memory processes may contribute to appetite regulation. When people look at palatable foods, their desire to consume them depends upon memory retrieval (i.e., recalling if it will taste good). If memory inhibition occurs during satiety, then pleasant eating-related memories will not be retrieved, making eating less likely. In contrast, if memory inhibition is less efficient, pleasant food-related memories will be retrieved, the food will appear desirable, and the chance of consumption increases. Here we tested whether a putative measure of memory inhibition could predict post-meal snack food intake. Study participants looked at palatable snacks and judged their desire to eat them (i.e., a memory-dependent process), and then ate a small sample of each food, and rated them for liking (i.e., an orosensory-dependent process) - all using category rating scales. Following a filling meal, this test was repeated, alongside others. Finally, participants were given the opportunity for ad libitum snack food consumption, in addition to collecting measures such as impulsivity. Poorer memory inhibition (i.e., smaller changes in wanting relative to liking from pre-to post-meal) was associated with greater consumption of snacks on the ad libitum test (Sr2% = 4.4, p = 0.006) after controlling for other variables likely to influence eating (e.g., impulsivity). This effect was maintained even when the memory inhibition measure was based on foods different to those being consumed on the ad libitum snacking test. In conclusion, memory inhibition may contribute to food intake regulation, and when this is less efficient, more palatable food is likely to be eaten in the post-meal period.

The internal (i.e., interoceptive) sensations that characterise hunger vary between people, and this may also be the case for thirst, although it has not been so well explored. There are probably both heritable and learning-based causes for this interoceptive variability. Consequently, it would seem plausible that parents and their offspring would have more similar patterns of hunger and thirst than pairs of strangers. We tested this idea, in addition to exploring its potential moderating variables, by studying the similarity of self-reported hunger and thirst sensations in 170 students and their primary caregivers from childhood. Both students and caregivers completed the same online-survey, covering hunger and thirst sensations, beliefs about the causes of hunger and thirst, the Three Factor Eating Questionnaire (revised) and demographic data. We find evidence of robust student-caregiver similarity in interoceptive hunger and thirst sensations (medium effect sizes), with these being moderated by caregiver beliefs about the homeostatic nature of each state (medium effect sizes). This suggests a potential role for caregivers in the development of their offspring's interoceptive cues for hunger and for thirst. In addition, thirst, like hunger, appears to be multidimensional, and varies between people. The implications of these findings are discussed.

There appears to be no attempt to categorize the specific classes of behavior that the tactile system underpins. Awareness of how an organism uses touch in their environment informs understanding of its versatility in non-verbal communication and tactile perception. This review categorizes the behavioral functions underpinned by the tactile sense, by using three sources of data: (1) Animal data, to assess if an identified function is conserved across species; (2) Human capacity data, indicating whether the tactile sense can support a proposed function; and (3) Human impaired data, documenting the impacts of impaired tactile functioning (e.g., reduced tactile sensitivity) for humans. From these data, three main functions pertinent to the tactile sense were identified: Ingestive Behavior; Environmental Hazard Detection and Management; and Social Communication. These functions are reviewed in detail and future directions are discussed with focus on social psychology, non-verbal behavior and multisensory perception.

Interoceptive individual differences have garnered interest because of their relationship with mental health. One type of individual difference that has received little attention is variability in the sensation/s that are understood to mean a particular interoceptive state, something that may be especially relevant for hunger. We examined if interoceptive hunger is multidimensional and idiosyncratic, if it is reliable, and if it is linked to dysfunctional eating and beliefs about the causes of hunger. Participants completed a survey just before a main meal, with most retested around 1 month later. We found that interoceptive hunger has 11 dimensions, and while people differ considerably in their combinations of interoceptive hungers, these represent only 4% of all possible permutations. Hunger reports were reliable. We found relationships between variability in hunger interoception and dysfunctional eating, especially for uncontrolled eating. We also found that hunger beliefs were in some cases strongly related to aspects of hunger interoception. The implications of these findings are discussed.

Recent research has characterized the behavioral defense against disease. In particular the detection of sickness cues, the adaptive reactions (e.g. avoidance) to these cues and the mediating role of disgust have been the focus. A presumably important but less investigated part of a behavioral defense is the immune system response of the observer of sickness cues. Odors are intimately connected to disease and disgust, and research has shown how olfaction conveys sickness cues in both animals and humans. This study aims to test whether odorous sickness cues (i.e. disgusting odors) can trigger a preparatory immune response in humans. We show that subjective and objective disgust measures, as well as TNFα levels in saliva increased immediately after exposure to disgusting odors in a sample of 36 individuals. Altogether, these results suggest a collaboration between behavioral mechanisms of pathogen avoidance in olfaction, mediated by the emotion of disgust, and mechanisms of pathogen elimination facilitated by inflammatory mediators. Disgusting stimuli are associated with an increased risk of infection. We here test whether disgusting odors, can trigger an immune response in the oral cavity. The results indicate an increase level of TNFα in the saliva. This supports that disease cues can trigger a preparatory response in the oral cavity.

INTRODUCTION:The COVID-19 pandemic impacted clinical research worldwide potentially altering research findings. The study purpose was to measure the effect of the pandemic on recruitment, retention, assessment, and intervention completion rates. METHODS:Enrollment and participation data from a clinical trial evaluating efficacy of a physical therapy intervention for high-risk preterm infants were compared across 3 pandemic periods (February 2019 through November 2021). RESULTS:Recruitment, retention, assessment, and intervention completion rates were lowest during the peak pandemic period. CONCLUSIONS:In compliance with the Human Subjects Review Board, and for the participants' and staff safety, transition from in-person to telehealth or hybrid visits was required to continue this longitudinal study. Despite the negative effect of the pandemic, parental resilience and commitment to the study was clear. Flexibility, quick action, dedication, and efficiency of the research team were key elements enabling study continuation with successful transition to telehealth assessments/interventions during the peak pandemic period.