Action ability modulates time-to-collision judgments

• Type of Material: Article
• Authors: Eleonora Vagnoni, University of London; Vasiliki Andreanidou, University of London; Stella Lourenco, Emory University; Matthew R. Longo, University of London
• Language: English
• Date: 2017-09
• Publisher: Springer Verlag (Germany)
• Publication Version: Final Published Version
• Copyright Statement: © The Author(s) 2017
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1007/s00221-017-5008-2
• Title of Journal or Parent Work: Experimental Brain Research
• ISSN: 0014-4819
• Volume: 235
• Issue: 9
• Start Page: 2729
• End Page: 2739
• Grant/Funding Information: E.V. was supported by a studentship from the Economic and Social Research Council. M.R.L. was supported by European Research Council Grant ERC-2013-StG-336050 under the FP7.
• Keywords: Peripersonal space representation; Emotion; Motor ability; Action ability; Looming; Time-to-collision
• Research Categories: Psychology, General

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.