title: Compression of Space for Low Visibility Probes.
abstract: Stimuli briefly flashed just before a saccade are perceived closer to the saccade target, a phenomenon known as perisaccadic compression of space (Ross et al., 1997). More recently, we have demonstrated that brief probes are attracted towards a visual reference when followed by a mask, even in the absence of saccades (Zimmermann et al., 2014a). Here, we ask whether spatial compression depends on the transient disruptions of the visual input stream caused by either a mask or a saccade. Both of these degrade the probe visibility but we show that low probe visibility alone causes compression in the absence of any disruption. In a first experiment, we varied the regions of the screen covered by a transient mask, including areas where no stimulus was presented and a condition without masking. In all conditions, we adjusted probe contrast to make the probe equally hard to detect. Compression effects were found in all conditions. To obtain compression without a mask, the probe had to be presented at much lower contrasts than with masking. Comparing mislocalizations at different probe detection rates across masking, saccades and low contrast conditions without mask or saccade, Experiment 2 confirmed this observation and showed a strong influence of probe contrast on compression. Finally, in Experiment 3, we found that compression decreased as probe duration increased both for masks and saccades although here we did find some evidence that factors other than simply visibility as we measured it contribute to compression. Our experiments suggest that compression reflects how the visual system localizes weak targets in the context of highly visible stimuli.
authors.affiliation: Centre Attention & Vision, Laboratoire Psychologie de la Perception, Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR 8242Paris, France; Equipe Cognition Visuelle, Faculté de Psychologie et des Sciences de l'Education, Université de GenèveGenève, Switzerland.
authors.forename: Sabine
authors.initials: S
authors.lastname: Born
authors.affiliation: Centre Attention & Vision, Laboratoire Psychologie de la Perception, Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR 8242 Paris, France.
authors.forename: Hannah M
authors.initials: HM
authors.lastname: Krüger
authors.affiliation: Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Jülich Jülich, Germany.
authors.forename: Eckart
authors.initials: E
authors.lastname: Zimmermann
authors.affiliation: Centre Attention & Vision, Laboratoire Psychologie de la Perception, Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR 8242Paris, France; Department of Psychological and Brain Sciences, Dartmouth CollegeHanover, NH, USA.
authors.forename: Patrick
authors.initials: P
authors.lastname: Cavanagh
keywords: compression of space; masking; mislocalization; saccades; spatial perception; visibility