Pictures of you: Dot stimuli cause motor contagion in presence of a still human form

The ownership memory self-reference effect shifts recognition criterion but not recognition sensitivity

Information referenced to the self is retrieved more accurately than information referenced to others, known as the memory self-reference effect. It is unclear, however, whether social context (identity of the other) or task factors alter decision-making processes. In a virtual object allocation task, female participants sorted objects into their own or another's (stranger or mother) basket based on a colour cue. Subsequently, they performed a recognition memory task in which they first indicated whether each object was old or new, and then whether it had been allocated to themselves or to the other. We obtained owner-specific hit rates and false-alarm rates and applied signal detection theory to derive separate recognition sensitivity (d') and recognition criterion parameters (c) for self- and other-owned objects. While there was no clear evidence of a recognition self-reference effect, or a change in sensitivity, participants adopted a more conservative recognition criterion for self- compared with other-owned objects, and particularly when the other-referent was the participant's mother compared with the stranger. Moreover, when discriminating whether the originally presented objects were self- or other-owned, participants were biased toward ascribing ownership to the 'other'. We speculate that these findings reflect ownership-based changes in decisional processing during the recognition memory self-reference paradigm.

Top-Down Modulation of Motor Priming by Belief About Animacy

Research has shown that people automatically imitate others and that this tendency is stronger when the other person is a human compared with a nonhuman agent. However, a controversial question is whether automatic imitation is also modulated by whether people believe the other person is a human. Although early research supported this hypothesis, not all studies reached the same conclusion and a recent meta-analysis found that there is currently neither evidence in favor nor against an influence of animacy beliefs on automatic imitation. One of the most prominent studies supporting such an influence is the study by Liepelt and Brass (2010), who found that automatic imitation was stronger when participants believed an ambiguous, gloved hand to be human, as opposed to wooden. In this registered report, we provide a high-powered replication of this study (N = 199). In contrast to Liepelt and Brass (2010), we did not find an effect of animacy beliefs on automatic imitation. However, we did find a correlation between automatic imitation and perceived self-other similarity. Together, these results suggest that the gloved hand procedure does not reliably influence automatic imitation, but interindividual differences in perceived similarity do.

Biological motion elicits between-person Inhibition of Return in temporal and spatial movement parameters

The present study was designed to gain a deeper understanding of the processing of biological motion stimuli. To this end, we investigated if the inhibition of return (IoR) effect emerges in initiation times and trajectories of pointing movements to targets in left and right space where the preceding cues were pointing movement of a human model or a dot with the same biological motion. Targets were randomly presented in the same or opposite side from the direction of the motion cue. It was hypothesised that the visuomotor system should resonate with the biological motion of a dot, but that the human model should exaggerate the effect. Thus, the human model should trigger stronger attention shifts compared with the dot model and lead to more robust IoR effects in both spatial (movement) and temporal parameters of the observer's pointing responses. Initiation times and the spatial parameters (angle of the hand trajectory) of the pointing movements were analysed. Results indicate that facilitation and IoR effects triggered by human and dot stimuli did not differ. Based on these findings, it seems that the crucial feature of motion cues that generate shifts in attention is biological motion, rather than human appearance per se.

Self-bias effect: movement initiation to self-owned property is speeded for both approach and avoidance actions

Recall of, and physical interaction with, self-owned items is privileged over items owned by other people (Constable et al. in Cognition 119(3):430-437, 2011; Cunningham et al. in Conscious Cognit 17(1):312-318, 2008). Here, we investigate approach (towards the item), compared with avoidance (away from the item) movements to images of self- and experimenter-owned items. We asked if initiation time and movement duration of button-press approach responses to self-owned items are associated with a systematic self-bias (overall faster responses), compared with avoidance movements, similar to findings of paradigms investigating affective evaluation of (unowned) items. Participants were gifted mugs to use, and after a few days they completed an approach-avoidance task (Chen and Bargh in Pers Soc Psychol Bull 25(2):215-224, 1999; Seibt et al. in J Exp Soc Psychol 44:713-720, 2008; Truong et al. in J Exp Psychol Hum Percept Perform 42(3), 375-385, 2016) to images of their own or the experimenter's mug, using either congruent or incongruent movement direction mappings. There was a self-bias effect for initiation time to the self-owned mug, for both congruent and incongruent mappings, and for movement duration in the congruent mapping. The effect was abolished in Experiment 2 when participants responded based on a shape on the handle rather than mug ownership. We speculate that ownership status requires conscious processing to modulate responses. Moreover, ownership status judgements and affective evaluation may employ different mechanisms.

Biological motion and animacy belief induce similar effects on involuntary shifts of attention

Biological motion is salient to the human visual and motor systems and may be intrinsic to the perception of animacy. Evidence for the salience of visual stimuli moving with trajectories consistent with biological motion comes from studies showing that such stimuli can trigger shifts of attention in the direction of that motion. The present study was conducted to determine whether or not top-down beliefs about animacy can modify the salience of a nonbiologically moving stimulus to the visuomotor system. A nonpredictive cuing task was used in which a white dot moved from a central location toward a left- or right-sided target placeholder. The target randomly appeared at either location 200, 600, or 1,300 ms after the motion onset. Five groups of participants experienced different stimulus conditions: (1) biological motion, (2) inverted biological motion, (3) nonbiological motion, (4) animacy belief (paired with nonbiological motion), and (5) computer-generated belief (paired with nonbiological motion). Analysis of response times revealed that the motion in the biological motion and animacy belief groups, but not in the inverted and nonbiological motion groups, affected processing of the target information. These findings indicate that biological motion is salient to the visual system and that top-down beliefs regarding the animacy of the stimulus can tune the visual and motor systems to increase the salience of nonbiological motion.

Top-down attentional factors modulate action priming in reach-to-grasp action

Previous studies report that viewing exaggerated, high-lifting reaches (versus direct reaches) primes higher vertical deviation in wrist trajectory in the observer's subsequent reaches (trajectory priming), but it is unclear to what extent this effect depends upon task instructions relevant to top-down attention. In two experiments, participants were instructed to gaze at a dot presented on a large monitor for a colour-change go signal that cued them to execute a direct reach to a target. In the background, the monitor also displayed life-sized films of a human model. The films were of the model either remaining still or reaching to grasp a target with either a direct trajectory or an exaggerated, high-lifting trajectory. When the dot traced the human model's wrist throughout her movement, a robust trajectory priming effect emerged. When the dot remained stationary in a central location but the human model reached in the background, the human model's trajectory did not alter the participants' trajectories. Finally, when the dot traced exaggerated and direct trajectories and the human model remained stationary, the dot's movement produced an attenuated, non-significant trajectory priming effect. These findings show that top-down attentional factors modulate trajectory priming. In addition, a moving non-human stimulus does not produce the same degree of action priming when contextual factors make salient its independence of human agency and/or intention.