Motion upside-down: Response priming with inverted biological primes

The ability to perceive and quickly process biological motion is a key aspect in human information processing that allows for rapid reactions. Previous research demonstrated a strong activation elicited by biological movements as primes in response priming. Research has shown that for biological stimuli in general, a change in orientation can strongly affect perception, information extraction, and attention shifting. However, it is unclear whether motor activation is subject to this influence. The response priming paradigm is a suitable tool in cognitive psychology to investigate motor preactivations in general. Here, two experiments investigate the behavioral priming effects of upside-down presented biological movements on static targets in different SOAsteps. We use two stimuli for biological movements: a dynamic point-light walker (Experiment 1) and a face with a dynamic gaze (Experiment 2). Both stimuli are compared to their upright versions. While with upright biological movements, we replicate strong PCEs in both experiments, an upside-down PLW led to significantly weaker PCEs, suggesting an attenuation of priming effects through inversion. Interestingly, a scrambled-dot condition led to sustained PCEs, suggesting possible preserved local motion trajectories. As to gaze primes, both an upright and an upside-down version produced equally strong PCEs with a decline at a longer SOA. Motor activation elicited by gaze movement direction is sustained and independent from orientation. Our findings show that inversion can affect motor activation in biological motion processing. This influence, however, depends on the nature of the stimulus.