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Attention, Perception, & Psychophysics© The Author(s) 201210.3758/s13414-012-0397-6 The perceived onset position of a moving target: Effects of trial contexts are evoked by different attentional allocations Jochen Müsseler1, 2   and Jens Tiggelbeck1

RWTH Aachen University, Aachen, Germany
Work and Cognitive Psychology, RWTH Aachen University, Jägerstr. 17-19, 52066 Aachen, Germany  
Jochen Müsseler
URL: Published online: 14 November 2012
Previous studies have shown that the localization of the perceived onset position of a moving target varies with the trial context. When the moving target appeared at predictable positions to the left or right of fixation (constant context), localization judgments of the perceived onset positions were essentially displaced in motion direction (Fröhlich effect). In contrast, when the target appeared at unpredictable positions in the visual field (random context), localization judgments were at least drastically reduced. Four explanations of this influence of trial context on localization judgments were examined in three experiments. Findings ruled out an overcompensation mechanism effective in random-context conditions, a predictive mechanism effective in constant-context conditions and a detrimental mechanism originating from more trial repetitions in constant-context conditions. Instead, the results indicated that different attentional allocations are responsible for the localization differences. They also demonstrated that attentional mechanisms are at the basis of the Fröhlich effect. Keywords

 Attention Space perception Localization Position judgments Onset position Moving stimuli Motion Fröhlich effect Introduction
Perception of the initial phase of a moving target is subject to several psychophysical distortions. At the beginning of a constant motion, observers estimate velocity as being higher than in later phases of the motion; thus, they have the impression of a deceleration. Consequently, when a motion that accelerates in the initial phase is presented, observers judge it as having a constant velocity (e.g., Brouwer, Brenner, & Smeets, 2002; Runeson, 1974; Tayama, 2004). Another perceptual distortion is that target discrimination is impaired for targets presented at initial positions of motion onset (Ansorge, Carbone, Becker, & Turatto,2010; Müsseler & Aschersleben, 1998). The present study is concerned with two opposed localization errors when observers were asked to indicate the initial position of a moving target. Either they mislocalized the target’s onset position consistently in the direction of motion (the Fröhlich effect; Fröhlich, 1923; for a recent overview, see Kerzel, 2010), or the target’s onset was consistently mislocalized in the direction opposite to motion (the onset repulsion effect; cf. Thornton, 2002; see also Actis-Grosso & Stucchi, 2003; Hubbard & Motes, 2002; Hubbard & Ruppel, 2011; Kerzel, 2010). In an effort to explain the discrepancy between the two sets of observations, Müsseler and Kerzel (2004; see also Müsseler, Stork, & Kerzel, 2008) found that the spatial predictability of the target onset position varied between studies. When the spatial onset predictability was high, targets appeared at a fairly constant eccentricity to the left and right of fixation (constant-context condition; cf. Müsseler & Aschersleben, 1998). When spatial onset predictability was low, the target’s onset was random within a large square field centered on fixation (random-context condition; cf. Thornton, 2002). In the experiments of Müsseler and Kerzel, the same onset positions as in the...
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