Priming of hand and foot response: is spatial attention to the body site enough?

"The clothes (and the face) make the Starman": Facial and clothing features shape self-other matching processes between human observers and a cartoon character

Anthropomorphization occurs when human characteristics are attributed to nonhuman animals or objects. One process that could facilitate the anthropomorphization of nonhuman animals may be a self-other body-part matching mechanism wherein the body of the nonhuman animal is conceptually mapped to the human observer's representation of their body. The present study was designed to determine if specific features could facilitate body-part matching between the cartoon of a nonhuman animal and human observers. Participants responded to targets presented on the cartoon of a starfish. In No Structure conditions, dots and curved lines were distributed evenly within the starfish. In Face conditions, two dots and one curved line represented eyes and a mouth of a "face". In Clothes conditions, dots and lines represented a shirt and pants. Body-part matching emerged when the image had a face or clothing, but did not emerge in No Structure conditions. These studies provide unique evidence that the anthropomorphization of a nonhuman cartoon may be facilitated by human-like internal features on the image.

Hand, but not foot, cues generate increases in salience at the pointed-at location

One line of research has indicated that directional social cues, such as eye gaze and pointed fingers, increase the salience of spatial locations or objects in a relatively involuntary manner (social cueing effect). A separate line of research has indicated that the compatibility between the body part that is observed by an actor primes and facilitates responses with a similar body part more than a dissimilar body part (body-part compatibility effect). The present experiment investigated whether or not social cueing effects were modulated by the relationship between the responding effector and the body part observed as the cue. To this end, non-predictive directional hand or foot cues were presented 100 or 1000 ms prior to a target. On different blocks of trials, participants (n = 19) executed discrete hand-button and foot-pedal responses to the location of a target to examine the influence of cue-effector body-part compatibility on social cueing effects. Response times (RTs) of both hand and foot responses were shorter to cued targets than to uncued targets when hand cues were used. No cueing effects emerged when foot cues were used, regardless of the responding effector. These results suggest changes in salience following social cues are determined by the body part used as the cue and are not modulated by the compatibility between the limb used as the cue and effector. Overall, the social relevance and learned use of a cue seem more pertinent than body-part matching of a stimulus type and response effector in social cueing.

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

Observing moving body parts can automatically activate topographically corresponding motor representations in the primary motor cortex (M1), the so-called direct matching. Novel neurophysiological findings from social contexts are nonetheless proving that this process is not automatic as previously thought. The motor system can flexibly shift from imitative to incongruent motor preparation, when requested by a social gesture. In the present study we aim to bring an increase in the literature by assessing whether and how diverting overt spatial attention might affect motor preparation in contexts requiring interactive responses from the onlooker. Experiment 1 shows that overt attention—although anchored to an observed biological movement—can be captured by a target object as soon as a social request for it becomes evident. Experiment 2 reveals that the appearance of a short-lasting red dot in the contralateral space can divert attention from the target, but not from the biological movement. Nevertheless, transcranial magnetic stimulation (TMS) over M1 combined with electromyography (EMG) recordings (Experiment 3) indicates that attentional interference reduces corticospinal excitability related to the observed movement, but not motor preparation for a complementary action on the target. This work provides evidence that social motor preparation is impermeable to attentional interference and that a double dissociation is present between overt orienting of spatial attention and neurophysiological markers of action observation.