What do a chilly reception, a cold-blooded murder, and an icy stare have in common? Each plumbs the bulb of what could be called your social thermometer, exposing our reflexive tendency to conflate social judgments—estimations of another’s trust and intent — with the perception of temperature. Decades of fascinating cross-disciplinary studies have illuminated the surprising speed, pervasiveness and neurobiology of this unconscious mingling of the personal and the thermal.

The blurring of ‘heat’ and ‘greet’ is highlighted in a recent experiment by Ohio University’s Matthew Vess, who asked whether this tendency is influenced by an individual’s sensitivity to relational distress. They found that people high in the psychological attribute called attachment anxiety (a tendency to worry about the proximity and availability of a romantic partner) responded to memories of a relationship breakup with an increased preference for warm-temperature foods over cooler ones: soup over crackers. Subjects low in attachment anxiety — those more temperamentally secure — did not show this “comfort food” effect.

In a related part of the same experiment, subjects were asked to reconstruct jumbled words into sentences that had either cold or warm evocations. (Sentence reconstruction tasks involving specific themes are known to unconsciously influence subsequent behavior.) After being temperature-primed, Vess’s subjects rated their perceptions of their current romantic relationship. As in the first condition, subjects higher in attachment anxiety rated their relationship satisfaction higher when prompted with balmier phrases than with frosty ones.

 The fact that individual differences in a relationship-oriented trait (attachment anxiety) are related to a person’s sensitivity to unconscious temperature-related cues speaks to the “under the hood” unconscious mingling that occurs between our social perceptual system and our temperature perception system. Though people predisposed to worry about their relationships seem to be more sensitive to these cues, we are all predisposed to the blurring of different types of experience. Similar recent experiments have demonstrated, for example, that briefly holding a warm beverage buoys subsequent ratings of another’s personality, that social isolation sensitizes a person to all things chilly, that inappropriate social mimicry creates a sense of cold, and that differences in the setting of the experimental lab’s thermostat leads test subjects to construe social relationships differently.

 Vess’s experiments follow a much longer line of psychological research exploring the reasons people avoid a cold shoulder, lament a frigid partner and have to “cool off” after a spat. In point of fact, the mercury in our social minds has been of interest since at least the 1940’s, when landmark work on impression-formation by the pioneering social psychologist Solomon Asch demonstrated the “striking and consistent differences of impression” created by substituting the words “warm” and “cold” into a hypothetical person’s personality profile. Since then, a panoply of studies of social perception in a host of cultures have validated the centrality of these temperate anchors in forming rapid unconscious impressions of a person.

It will come as no surprise that the ultimate confluence of the thermal and the personal happens between our ears. The neuroscientist Jaak Panksepp, for example, has noted that the neural machinery for attachment and bonding is actually cobbled together out of more primitive brain areas used for temperature regulation. Adding to this theme, the psychiatrist Myron Hofer’s seminal research in the 1970’s demonstrated that certain parameters of rodent maternal attachment behavior (e.g. variations in touch or warmth) act as “hidden regulators” of various physiological responses (e.g.digestion) in their pups. Around the same time, another psychiatrist, John Bowlby, penned his now-canon observations about the central importance of attachment for the social and psychological development of young humans, reminding us that we are just another part of a chain of mammals that depend on the care of others for survival.

 The new work is also part of a field called grounded or embodied cognition. Basically, this ever-growing understanding of human mental function notes that all ideas and concepts—including hard-to-grasp ones like personality and trustworthiness—are ultimately anchored in concrete situations that happen to flesh-bound bodies. For example, our faces respond to disconcerting behavior (incest) in a similar way to disgusting ingestive behavior (crunching a cockroach). Moral from oral.

In the realm of relationships, this mingling of the less and more-concrete means that attachment experiences with specific others, their unconscious emotional tone, and the temperatures they actually feel activate and are stored in overlapping networks of brain areas. These are the so-called multimodal brain regions (a key one is called the insula) that blend different channels of sensory experience into a singular whole. In individual brains, then, the multichannel experience of being safe with another (initially, a mother) is forever fused with the experienced physical warmth that comes with being safe, fed and held. At the level of both brain and experience, this multi-sensory co-experiencing forms a wordless bedrock that implicitly grounds relational language, interpersonal evaluation, social cognition, and even imagined ingestion. “Warm” triggers “trust,” as well as the reverse.

From these insights, other questions abound. Regarding the biology of attachment and warmth, for example, one wonders whether certain molecules—the attachment hormone oxytocin, for example — bias cognition and behavior in a balmier direction. After all, given its vital role in birth, nursing, and early attachment bonds, oxytocin has a strong unconscious association with warm milk, a tendency to inspire trust and generosity, and the capacity to make more benign the valuation of others. Oxytocin even boosts a persons’ perception of the warmth of their own personality, and a ‘warm touch’ intervention in married couples enhances oxytocin levels. On the opposite hormonal pole, might testosterone—which decreases trust — also make things seem colder?

My late, beloved father—a psychologist — had a puckish propensity to char the toast that was a mandatory component of his hand-made hot breakfast ritual. Thanks to social neuroscience, I can now better appreciate (and perpetuate) the wisdom of this ritual linking hot food with heart-felt.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist at the Boston Globe. He can be reached at garethideas AT gmail.com or Twitter @garethideas.