Keep away from danger: Dangerous objects in dynamic and static situations.

Behavioral and neuroscience studies have shown that objects observation evokes specific 25 affordances (i.e., action possibilities) and motor responses. Recent findings provide evidence 26 that even dangerous objects can modulate the motor system evoking aversive affordances. 27 This sounds intriguing since so far the majority of behavioral, brain imaging, and transcranial 28 magnetic stimulation studies with painful and dangerous stimuli strictly concerned the 29 domain of pain, excepted for evidence suggesting sensitivity to objects’ affordances when 30 neutral objects are located in participants’ peripersonal space. This study investigates whether 31 the observation of a neutral or dangerous object in a static or dynamic situation differently 32 influences motor responses, and the time-course of the dangerous objects’ processing. In 33 three experiments we manipulated: object dangerousness (neutral vs. dangerous); object 34 category (artifact vs. natural); manual response typology (press vs. release a key); object 35 presentation (Experiment 1: dynamic, Experiments 2 and 3: static); object movement 36 direction (Experiment 1: away vs. toward the participant) or size (Experiments 2 and 3: big 37 vs. normal vs. small). The task required participants to decide whether the object was an 38 artifact or a natural object, by pressing or releasing one key. Results showed a facilitation for 39 neutral over dangerous objects in the static situation, probably due to an affordance effect. 40 Instead, in the dynamic condition responses were modulated by the object movement 41 direction, with a dynamic affordance effect of neutral objects and an escape-avoidance effect 42 of dangerous objects (neutral objects were processed faster when they moved toward-43 approached the participant, whereas dangerous objects were processed faster when they 44 moved away from the participant). Moreover, static stimuli influenced the manual response 45 typology. These data indicate the emergence of dynamic affordance and escaping-avoidance 46 effects.