Automatic imitation? Imitative compatibility affects responses at high perceptual load.

Abstract

Imitation involves matching the visual representation of another’s action onto the observer’s own motor program for that action. However, there has been some debate regarding the extent to which imitation is “automatic”—that is, occurs without attention. Participants performed a perceptual load task in which images of finger movements were presented as distractors. Responses to target letter stimuli were performed via finger movements that could be imitatively compatible (requiring the same finger movement) or incompatible with the distractor movements: In this common stimulus–response compatibility manipulation, the stimulus set comprises images of the response movements, producing an imitative compatibility effect. Attention to the distractor movements was manipulated by altering perceptual load through increasing the number of nontarget letter stimuli. If imitation requires attention, then at high perceptual load, imitative compatibility should not affect response times. In contrast, imitative compatibility influenced response times at high perceptual load, demonstrating that distractor movements were processed. However, the compatibility effect was reversed, suggesting that longer response times at high perceptual load tap into an inhibitory stage of distractor movement processing. A follow-up experiment manipulating temporal delay between targets and distractor movements supported this explanation. Further experiments confirmed that nonmovement distractor stimuli in the same configuration produced standard perceptual load effects and that results were not solely due to effector compatibility. These data suggest that imitation can occur without attention.

Higher levels of motor competence are associated with reduced interference in action perception across the lifespan

“…Our results are in line with previously reported interference effects of action perception on action production and vice versa (e.g., Catmur, 2016;Hamilton et al, 2004;Kilner et al, 2003;Press, Bird, Walsh, & Heyes, 2008). Importantly, the memory condition did interfere with action perception less strongly than the finger-tapping condition: Producing an action while simultaneously perceiving a different action was more challenging than mentally rehearsing a sequence of letters and digits during action observation.…”

Overt orienting of spatial attention and corticospinal excitability during action observation are unrelated

“…In this perspective, if observing an action automatically triggers an increase in CE, then a perceived action should be processed even in the absence/reduction of attentional resources [23]. To the extent that attention is critical for direct matching to occur, instead, CE should diminish whenever a participant's attention is diverted from an observed movement.…”

“…Schuch and colleagues [30] in an EEG study investigated the mu rhythm (oscillatory activity over sensorimotor cortex) and reported stronger activations of the motor system—as revealed by mu rhythm suppression—when an observed grasping action was relevant to the observers’ task (i.e., when they were later judging the grasp than when judging a colour change). Taken together, these data seem to suggest that motor system activation during action observation can be automatic, but attentional filters are at play to limit unnecessary processing and mimicry of observed actions [but see [23] for alternative hypothesis].…”

Stimulus-Response Compatibility Effect: An Attempt to Replicate Cook’s ‘Automatic Imitation in a Strategic Context’

“…Although there is no doubt that human imitative behavior has an automatic aspect (Blakemore & Frith, 2005;Brass et al, 2000;Catmur, 2016;Pan & Hamilton, 2015;Stürmer et al, 2000), or that the automatic imitation is mediated by the human MNS (Heyes, 2011), we do not always imitate the observed actions of others in everyday life. There has been only limited behavioral study investigating the automaticity of human imitative behavior in naturalistic situations.…”