Enhanced Automatic Action Imitation and Intact Imitation-Inhibition in Schizophrenia

Abstract

Imitation plays a key role in social learning and in facilitating social interactions and likely constitutes a basic building block of social cognition that supports higher-level social abilities. Recent findings suggest that patients with schizophrenia have imitation impairments that could contribute to the social impairments associated with the disorder. However, extant studies have specifically assessed voluntary imitation or automatic imitation of emotional stimuli without controlling for potential confounders. The imitation impairments seen might therefore be secondary to other cognitive, motoric, or emotional deficits associated with the disorder. To overcome this issue, we used an automatic imitation paradigm with nonemotional stimuli to assess automatic imitation and the top-down modulation of imitation where participants were required to lift one of 2 fingers according to a number shown on the screen while observing the same or the other finger movement. In addition, we used a control task with a visual cue in place of a moving finger, to isolate the effect of observing finger movement from other visual cueing effects. Data from 33 patients (31 medicated) and 40 matched healthy controls were analyzed. Patients displayed enhanced imitation and intact top-down modulation of imitation. The enhanced imitation seen in patients may have been medication induced as larger effects were seen in patients receiving higher antipsychotic doses. In sum, we did not find an imitation impairment in schizophrenia. The results suggest that previous findings of impaired imitation in schizophrenia might have been due to other cognitive, motoric, and/or emotional deficits.

Fig. 1.

Example of the 5 frames shown in the imitation task (a) and the 3 frames shown in the control task (b). Both examples are from congruent trials. The first frame in both tasks displayed a resting hand that was shown for 800–2.400 ms. In the imitation task, the second (34 ms), third (34 ms), and fourth frame (500 ms) displayed the number 1 or 2 between the 2 fingers and the lifting movement of one of the fingers. In the control task, the second frame displayed the number 1 or 2 between the 2 fingers and one of the fingers was covered by a mask (display time: 568 ms). The last frame in both tasks was a blank screen, which remained blank until the participant had placed both fingers back on the keyboard. In both tasks, this screen appeared when the participant lifted a finger. Reprinted from Cook and Bird (2012).

Fig. 2.

Mean reaction times (RTs) during congruent (a) and incongruent trials (b) in the imitation and control tasks for each group. Error bars: ±1 SEM.