Action ability modulates time-to-collision judgments

Eleonora Vagnoni,Stella F. Lourenco,Matthew R. Longo,Vasiliki Andreanidou

doi:10.1007/s00221-017-5008-2

Eleonora Vagnoni, Stella F. Lourenco + Show 2 more

Open Access

https://doi.org/10.1007/s00221-017-5008-2

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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.

Highlights

In vision, looming refers to a specific pattern of optical expansion of a surface or surface patch during direct approach towards a viewer (Gibson 1958)
Regarding the time-to-collision judgments, for each participant, Z-scores were calculated for time-to-collision judgments, separately for each level of actual time-to-collision
We replicated the classic TTC underestimation effect with judged TTC being underestimated relative to actual TTC (McLeod and Ross 1983; Schiff and Oldak 1990; Neuhoff 2001)

Summary

Introduction

In vision, looming refers to a specific pattern of optical expansion of a surface or surface patch during direct approach towards a viewer (Gibson 1958). Underestimating TTC yields more time to engage in preparatory defensive behaviours Such a bias is, technically speaking, an error, the cost of a false positive (making preparatory actions too early) is far less than the cost of a false negative (making preparatory actions too late; Haselton and Nettle 2006). Following this logic, Neuhoff and colleagues have argued that perceiving and acting in response to looming stimuli depends on perceptual abilities, and on the motor capabilities of the observer (Neuhoff et al 2012). The authors (Neuhoff et al 2012) demonstrated how physical fitness modulates TTC judgments with listeners with poorer physical fitness showing a greater underestimation of the arrival time of looming sounds than listeners with better physical fitness

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