The principle of neural reuse and the various competing theories regarding its underlying mechanisms are of great value to the understanding of a growing body of findings within social psychology – those in which concrete physical sensations are shown to influence higher-order processes involved in trust, interpersonal and situational evaluation, and interpersonal behavior. For example, briefly holding a cup of hot (versus iced) coffee just before an impression formation task involving the identical set of information about a given target person changes that impression (Williams & Bargh Reference Williams and Bargh2008a): those who had contact with the warm cup subsequently judged the person as warmer (more prosocial, generous, helpful; see Fiske et al. Reference Fiske, Cuddy and Glick2007) than did those in the cold-coffee condition. (The effect was specific to variables related to interpersonal warmth, and not an overall positivity effect, as the coffee-temperature manipulation did not affect impression judgments on dimensions unrelated to prosocial behavior.) In a second study, those in the warm-coffee condition were more likely to give their compensation for being in the experiment to a friend (in the form of a gift certificate), whereas those in the cold-coffee condition were more likely to keep it for themselves. Thus, physical experiences of warmth directly influence perceptions of psychological warmth in another person, as well as the participant's own behavioral warmth towards others (see also IJzerman & Semin Reference IJzerman and Semin2009; Zhong & Leonardelli Reference Zhong and Leonardelli2008).

Similarly, perceptions of physical distance produce corresponding analogous influences on perceptions of psychological and emotional distance. Merely plotting two points on Cartesian graph paper that are relatively far versus close together on the page causes participants to feel more psychologically distant from their friends and family, and, in further studies, to show less physiological reactivity to emotionally laden photographs (i.e., more emotionally distant; see Williams & Bargh Reference Williams and Bargh2008b; Williams et al. Reference Williams, Bargh, Nocera and Gray2009a).

In both cases, these effects were predicted in part from the observed ubiquity of priming effects in social psychology in which incidental stimuli are shown to influence higher-order cognitive and behavioral outcomes without the individual's awareness or appreciation of this influence (see, e.g., Dijksterhuis et al. Reference Dijksterhuis, Chartrand, Aarts and Bargh2007). These priming effects have become so prevalent that the prevalence itself requires an explanation (Bargh Reference Bargh2006). Ours (Bargh & Morsella Reference Bargh and Morsella2008; Williams et al. Reference Williams, Huang and Bargh2009b) involved the notion of scaffolding, in which the development of more abstract concepts is said to be grounded in earlier-formed concrete concepts (such as spatial concepts that form in infancy and young childhood out of the comprehension of the physical world; Clark Reference Clark and Moore1973; Mandler Reference Mandler1992), or exapted from pre-existing innate structures such as evolved motivations for reproduction and survival (Huang & Bargh Reference Huang and Bargh2008). In this manner, associative connections develop between the original physical and the analogous later psychological versions of the concept (warmth, distance), creating multiple physical avenues for psychological priming effects in adults.

It is also possible that such warmth and distance effects have an innate basis. The attachment theorist John Bowlby (Reference Bowlby1969) notably argued that distance information was of survival relevance to many, if not all, organisms, because it facilitates both keeping close to caretakers when young and vulnerable, as well as the dispersal of conspecifics to reduce competition for scarce resources, as in territoriality behavior. And, at least in the case of primates, Harlow's (Reference Harlow1958) pioneering studies of monkeys raised alone showed the importance of early warmth experiences in infancy for successful social functioning as adults; those raised with a cloth mother, with a 100-watt light bulb behind the cloth, adapted much better than did the other parent-less monkeys.

The physical-to-psychological effects are not limited to warmth and distance, and may instead represent a general phenomenon involving many forms of sensory experience. For example, six experiments reported recently by Ackerman et al. (Reference Ackerman, Nocera and Bargh2010) reveal how the sense of touch influences analogously related psychological variables. Holding a relatively heavy (versus light) clipboard on which to evaluate a job candidate causes evaluators to see the candidate as more serious (heavy=serious) about his or her work and also causes the evaluators to take their own judgment task more seriously (they spend significantly longer on it). Working on a jigsaw puzzle with a rough versus smooth surface causes participants to subsequently rate an interpersonal interaction as going less (versus more) smoothly. Likewise, sitting on a hardwood versus cushioned chair produced greater rigidity (less attempt to compromise) in an interpersonal negotiation task.

Taken together, these demonstrations suggest a cognitive architecture in which social-psychological concepts metaphorically related to physical-sensory concepts – such as a warm person, a close relationship, and a hard negotiator – are grounded in those physical concepts, such that activation of the physical version also activates (primes) the more abstract psychological concept. Again, as in most priming research involving these social-psychological concepts and variables, the experimental participants are unaware of these potentially biasing influences on their social judgments and behavior and so do not correct or adjust for them (Wilson & Brekke Reference Wilson and Brekke1994).

The principle of neural reuse – specifically, that “local circuits may have low-level computational ‘workings’ that can be put to many different higher-level cognitive uses” (sect. 1.1, para. 5) – also helps to explain how activation of presumably evolved motivations, such as the mating (reproduction) goal, can exert influences outside of its focal domain of mating – effects that are difficult to understand under the principles of anatomical modularity or functional localization. For example, priming the mating goal influences the evaluation of other living kinds (flowers, fruits), as well in terms of “prime” life stages (Huang & Bargh Reference Huang and Bargh2008). Viewed in terms of the principle of reuse, this finding suggests that the mating goal makes use of a “prime lifestage” appraisal circuit, which is activated when the mating goal is primed and is thus influential in other domains as well, not exclusively mate selection.

Overall, these findings are in harmony with Anderson's central point that our mental carriers of meaning are tied to sensory experience to such an extent that one's physical state exerts a pervasive and often unconscious influence over the workings of the mind.