Humans automatically imitate other people's actions during social interactions, building rapport and social closeness in the process. Although the behavioral consequences and neural correlates of imitation have been studied extensively, little is known about the neural mechanisms that control imitative tendencies. For example, the degree to which an agent is perceived as human-like influences automatic imitation, but it is not known how perception of animacy influences brain circuits that control imitation. In the current fMRI study, we examined how the perception and belief of animacy influence the control of automatic imitation. Using an imitation–inhibition paradigm that involves suppressing the tendency to imitate an observed action, we manipulated both bottom–up (visual input) and top–down (belief) cues to animacy. Results show divergent patterns of behavioral and neural responses. Behavioral analyses show that automatic imitation is equivalent when one or both cues to animacy are present but reduces when both are absent. By contrast, right TPJ showed sensitivity to the presence of both animacy cues. Thus, we demonstrate that right TPJ is biologically tuned to control imitative tendencies when the observed agent both looks like and is believed to be human. The results suggest that right TPJ may be involved in a specialized capacity to control automatic imitation of human agents, rather than a universal process of conflict management, which would be more consistent with generalist theories of imitative control. Evidence for specialized neural circuitry that “controls” imitation offers new insight into developmental disorders that involve atypical processing of social information, such as autism spectrum disorders.

In a social setting, seeing Sally look at a clock means something different to seeing her gaze longingly at a slice of chocolate cake. In both cases, her eyes and face might be turned rightward, but the information conveyed is markedly different, depending on the object of her gaze. Numerous studies have examined brain systems underlying the perception of gaze direction, but less is known about the neural basis of perceiving gaze shifts to specific objects. During fMRI, participants observed an actor look toward one of two objects, each occupying a distinct location. Video stimuli were sequenced to obtain repetition suppression (RS) for object identity, independent of spatial location. In a control condition, a spotlight highlighted one of the objects, but no actor was present. Observation of the human actor's gaze compared with the spotlight engaged frontal, parietal, and temporal cortices, consistent with a broad action observation network. RS for gazed object in the human condition was found in posterior intraparietal sulcus (pIPS). RS for highlighted object in the spotlight condition was found in middle occipital, inferior temporal, medial fusiform gyri, and superior parietal lobule. These results suggest that human pIPS is specifically sensitive to the type object that an observed actor looks at (tool vs. food), irrespective of the observed actor's gaze location (left vs. right). A general attention or lower-level object feature processing mechanism cannot account for the findings because a very different response pattern was seen in the spotlight control condition. Our results suggest that, in addition to spatial orienting, human pIPS has an important role in object-centered social orienting.

When individuals acquire new skills, initial performance is typically better and tasks are judged to be easier when the tasks are segregated and practiced by block, compared to when different tasks are randomly intermixed in practice. However, subsequent skill retention is better for a randomly practiced group, an effect known as contextual interference (CI). The present study examined the neural substrates of CI using functional magnetic resonance imaging (fMRI). Individuals learned a set of three 4-element sequences with the left hand according to a block or random practice schedule. Behavioral retest for skill retention confirmed the presence of a typical CI effect with the random group outperforming the block group. Using a go/no-go fMRI paradigm, sequence preparation during the premovement study period was separated from movement execution. Imaging data for the two groups were compared for the first 1/3 and final 1/3 of training trials. Toward the end of training, behavioral performance between the two groups was similar, although the random group would later display a performance advantage on retention testing. During study time, the random group showed greater activity in sensorimotor and premotor regions compared to the block group. These areas are associated with motor preparation, sequencing, and response selection. This pattern of recruitment is consistent with the hypothesis that CI benefits in a sequencing task are due to improved capacity to actively prepare motor responses.