Action ability modulates time-to-collision judgments

Abstract

Time-to-collision (TTC) underestimation has been interpreted as an adaptive response that allows observers to have more time to engage in a defensive behaviour. This bias seems, therefore, strongly linked to action preparation. There is evidence that the observer’s physical fitness modulates the underestimation effect so that people who need more time to react (i.e. those with less physical fitness) show a stronger underestimation effect. Here we investigated whether this bias is influenced by the momentary action capability of the observers. In the first experiment, participants estimated the time-to-collision of threatening or non-threatening stimuli while being mildly immobilized (with a chin rest) or while standing freely. Having reduced the possibility of movement led participants to show more underestimation of the approaching stimuli. However, this effect was not stronger for threatening relative to non-threatening stimuli. The effect of the action capability found in the first experiment could be interpreted as an expansion of peripersonal space (PPS). In the second experiment, we thus investigated the generality of this effect using an established paradigm to measure the size of peripersonal space. Participants bisected lines from different distances while in the chin rest or standing freely. The results replicated the classic left-to-right gradient in lateral spatial attention with increasing viewing distance, but no effect of immobilization was found. The manipulation of the momentary action capability of the observers influenced the participants’ performance in the TTC task but not in the line bisection task. These results are discussed in relation to the different functions of PPS.

The Interrelation Between Peripersonal Action Space and Interpersonal Social Space: Psychophysiological Evidence and Clinical Implications

“…Participants erroneously predicted a collision even though it was not physically possible. Because it is particularly difficult to keep track of moving stimuli following different velocities (Pylyshyn, 2004 ; Fencsik et al, 2007 ), one interpretation of these findings was that anticipating even erroneously collision event would provide an adaptive advantage by ensuring that individuals are allowed to prepare for appropriate behavior (Neuhoff, 1998 , 2001 ; Vagnoni et al, 2017 ). The specific way spatio-temporal information is processed may thus reflect the motor, anticipatory and adaptive function of the PPS that works like an alert system for timely preparing reactions to events that occur near the body (Coello and Iachini, 2020 ).…”

Frontier of Self and Impact Prediction

“…Interestingly, looming stimuli which are explicitly threatening are perceived as having a shorter time-to-impact latency in comparison to objects moving at the same objective speed and which are not threatening ( Vagnoni et al, 2012 ). This underestimation of approaching stimuli is also influenced by ones motor abilities, and is for example increased if subjects have their heads constrained by a chin rest compared to when standing freely ( Vagnoni et al, 2017 ), the former condition possibly indicating, due to the constraint, an increased threat relative to the unconstrained condition. The neuronal underlying of this observation is to our knowledge, completely unexplored.…”

What is peripersonal space? An examination of unresolved empirical issues and emerging findings

“…Like PPS representations that support non‐defensive behaviors, there is evidence that representations of PPS are flexible in defensive contexts. For example, Vagnoni, Andreanidou, Lourenco, and Longo (), Vagnoni, Lourenco, and Longo (), Vagnoni, Lourenco, and Longo () have reported that looming images of threatening stimuli (i.e., snakes and spiders) were judged as arriving sooner than nonthreatening stimuli (i.e., rabbits and butterflies) on a time‐to‐contact (TTC) task. One interpretation is that this effect could result from participants experiencing larger representations of PPS in the presence of evolutionary threatening animals as compared to nonthreatening animals, leading them to judge the former as making contact with themselves sooner.…”