Douglas Martin

Executive functioning and imitation: Increasing working memory load facilitates behavioural imitation

If perceptual and bodily states are closely linked and if perceiving action automatically leads to corresponding activations in ones own motor system, then why do not we imitate all the time? There is evidence suggesting that executive functioning (EF) may play a moderating role in inhibiting overt imitation [e.g. Luria, A. R. (1966). Higher cortical functions in man. New York: Basic Books]. In an experiment we tested this idea. 48 participants received either a high or low working memory (WM) load and were instructed to respond to either a finger cue or spatial cue with a finger movement. Results indicate that occupying WM facilitates reaction times to finger cues while responses to simple spatial cues are unchanged. The findings suggest that imitation is indeed a dominant response and EF is needed to inhibit the spontaneous tendency to imitate.

The Spontaneous Formation of Stereotypes via Cumulative Cultural Evolution

All people share knowledge of cultural stereotypes of social groups—but what are the origins of these stereotypes? We examined whether stereotypes form spontaneously as information is repeatedly passed from person to person. As information about novel social targets was passed down a chain of individuals, what initially began as a set of random associations evolved into a system that was simplified and categorically structured. Over time, novel stereotypes emerged that not only were increasingly learnable but also allowed generalizations to be made about previously unseen social targets. By illuminating how cognitive and social factors influence how stereotypes form and change, these findings show how stereotypes might naturally evolve or be manipulated.

Processing orientation and Emotion Recognition

There is evidence that some emotional expressions are characterized by diagnostic cues from individual face features. For example, an upturned mouth is indicative of happiness, whereas a furrowed brow is associated with anger. The current investigation explored whether motivating people to perceive stimuli in a local (i.e., feature-based) rather than global (i.e., holistic) processing orientation was advantageous for recognizing emotional facial expressions. Participants classified emotional faces while primed with local and global processing orientations, via a Navon letter task. Contrary to previous findings for identity recognition, the current findings are indicative of a modest advantage for face emotion recognition under conditions of local processing orientation. When primed with a local processing orientation, participants performed both significantly faster and more accurately on an emotion recognition task than when they were primed with a global processing orientation. The impacts of this finding for theories of emotion recognition and face processing are considered.

Processing style and person recognition: Exploring the face inversion effect

It has frequently been reported that recognition performance is impaired when faces are presented in an inverted rather than upright orientation, a phenomenon termed the face inversion effect (FIE). Extending previous work on this topic, the current investigation explored whether individual differences in global precedence—the propensity to process nonfacial stimuli in a configural manner—impacts memory for faces. Based on performance on the Navon letter-classification task, two experimental groups were created that differed in relative global precedence (i.e., strong global precedence [SGP] and weak global precedence [WGP]). In a subsequent face-recognition task, results revealed that while both groups demonstrated a reliable FIE, this effect was attenuated among participants displaying WGP. These findings suggest that individual differences in general processing style modulate face recognition.

Lateralized Repetition Priming for Unfamiliar Faces

Repetition priming (RP) is the ability to recognize a stimulus more rapidly as a result of prior exposure to the item. Recent research examining the neuroanatomical basis of this effect has demonstrated RP for familiar faces presented to the right but not to the left cerebral hemisphere. Extending this line of enquiry, the current research considered whether similar effects emerge when unfamiliar faces are the stimuli of interest. Using a divided-visual-field methodology, RP for unfamiliar faces in the left and the right hemispheres was assessed. The results revealed that RP: (i) only emerges in the right hemisphere; (ii) is evident regardless of whether the lateralized presentation of unfamiliar faces occurs at study or at test and (iii) occurs only when hair is cropped from the faces. The theoretical implications of these findings are considered.

Getting to know you: From view-dependent to view-invariant repetition priming for unfamiliar faces

Recent research suggests that repetition priming (RP) for unfamiliar faces is highly view dependent and is eliminated when the viewpoint of target faces changes between study and test. The current research examined whether increased familiarity with novel faces from a single viewpoint at study would support RP from an alternative viewpoint at test. Participants passively viewed novel face images from a single viewpoint at study (i.e., either front or three-quarters), with half of the images seen once and half seen on five occasions. During a sex classification task at test, participants were faster to respond to face images seen from the same view as that at study than they were to previously unseen distractor faces for both single exposure faces and faces seen on five occasions (i.e., standard RP). When, however, face images at test were shown from a different viewpoint from that at study, RP only occurred for faces viewed on five occasions.

Categorical proactive interference effects occur for faces

Recent research has demonstrated that proactive interference (PI) between the names of familiar individuals in a memory task is category specific, and that subsequent release from proactive interference (RPI) is a useful tool for investigating the underlying categorisation of memory for people. These RPI effects are in line with the influential Interactive Activation and Competition (IAC) model of person recognition, which predicts the existence of such categorical effects. Here we report an experiment precisely replicating the categorical PI and RPI effects found previously for occupational categories, but using faces instead of names as stimuli. The results underscore the use of PI as a tool to investigate semantic categorisation, are compatible with models proposing a single point of access to semantic information about people and provide further evidence for the categorical organisation of person knowledge.

Simulation-based mentalizing generates a “proxy” self-reference effect in memory

The self-reference effect (SRE) in memory is thought to depend on specialized mechanisms that enhance memory for self-relevant information. We investigated whether these mechanisms can be engaged “by proxy” when we simulate other people, by asking participants to interact with two virtual partners: one similar and one dissimilar to self. Participants viewed pairs of objects and picked one for themselves, for their similar partner, or their dissimilar partner. A surprise memory test followed that required participants to identify which object of each pair was chosen, and for whom. Finally, participants were shown both partners’ object pairs again, and asked to indicate their personal preference. Four key findings were observed. Overlap between participants’ own choice and those made for their partner was significantly higher for the similar than the dissimilar partner, revealing participants’ use of their own preferences to simulate the similar partner. Recollection of chosen objects was significantly higher for self than for both partners and, critically, was significantly higher for similar than dissimilar partners. Source confusion between self and the similar partner was also higher. These findings suggest that self-reference by proxy enhances memory for non-self-relevant material, and we consider the theoretical implications for functional interpretation of the SRE.

Explicit Mentalizing Mechanisms and Their Adaptive Role in Memory Conformity

Memory conformity occurs when an individual endorses what other individuals remember about past events. Research on memory conformity is currently dominated by a ‘forensic’ perspective, which views the phenomenon as inherently undesirable. This is because conformity not only distorts the accuracy of an individuals memory, but also produces false corroboration between individuals, effects that act to undermine criminal justice systems. There is growing awareness, however, that memory conformity may be interpreted more generally as an adaptive social behavior regulated by explicit mentalizing mechanisms. Here, we provide novel evidence in support of this emerging alternative theoretical perspective. We carried out a memory conformity experiment which revealed that explicit belief-simulation (i.e. using ones own beliefs to model what other people believe) systematically biases conformity towards like-minded individuals, even when there is no objective evidence that they have a more accurate memory than dissimilar individuals. We suggest that this bias is functional, i.e. adaptive, to the extent that it fosters trust, and hence cooperation, between in-group versus out-group individuals. We conclude that memory conformity is, in more fundamental terms, a highly desirable product of explicit mentalizing mechanisms that promote adaptive forms of social learning and cooperation.

Form-specific repetition priming for unfamiliar faces

It has frequently been demonstrated that repeated presentation of a stimulus can result in facilitated processing of the item, an effect termed repetition priming. Questions remain, however, regarding the boundary conditions of this effect, particularly for faces. For example, is repetition priming for unfamiliar faces dependent on the presentation of identical stimuli at study and test? This question was explored in three experiments in which the pose (i.e., frontal vs. (3/4)) and perceptual distance from the original facial identity (i.e., 100%, 75%, 50%, or 25% of original person) were manipulated between the testing phases of a standard repetition-priming paradigm. The results revealed that priming did not persist following any change to a face between study and test, thereby suggesting that repetition priming for unfamiliar faces is form specific. The theoretical implications of this finding are considered.