Abstract
Reaction time (RT) can strongly be influenced by a number of stimulus properties. For instance, there was converging evidence that perceived size rather than physical (i.e., retinal) size constitutes a major determinant of RT. However, this view has recently been challenged since within a virtual three-dimensional (3D) environment retinal size modulation failed to influence RT. In order to further investigate this issue in the present experiments response force (RF) was recorded as a supplemental measure of response activation in simple reaction tasks. In two separate experiments participants’ task was to react as fast as possible to the occurrence of a target located close to the observer or farther away while the offset between target locations was increased from Experiment 1 to Experiment 2. At the same time perceived target size (by varying the retinal size across depth planes) and target type (sphere vs. soccer ball) were modulated. Both experiments revealed faster and more forceful reactions when targets were presented closer to the observers. Perceived size and target type barely affected RT and RF in Experiment 1 but differentially affected both variables in Experiment 2. Thus, the present findings emphasize the usefulness of RF as a supplement to conventional RT measurement. On a behavioral level the results confirm that (at least) within virtual 3D space perceived object size neither strongly influences RT nor RF. Rather the relative position within egocentric (body-centered) space presumably indicates an object’s behavioral relevance and consequently constitutes an important modulator of visual processing.
Highlights
In everyday life the visual system is confronted with a vast majority of ambiguous information
The 2 × 2 × 2 analysis of variances (ANOVA) performed on force data revealed a significant main effect of Depth [FD(1,13) = 4.93, p = 0.045, η2G = 0.00012] indicating more forceful responses associated with near (1011.66 cN; pooled across retinal size and target type condition) as opposed to far targets (1003.97 cN)
Even though visual inspection of the data gives the impression that there is an response force (RF) effect between retinal size conditions this is rather inconsistent across participants and non-significant [FR(1,13) = 2.71, p > 0.123]
Summary
In everyday life the visual system is confronted with a vast majority of ambiguous information. In the past the mechanisms underlying visual perception and attention have often been investigated using twodimensional (2D) stimulus material, while only a minority of studies was concerned with the impact of 3D stimulus material (e.g., Downing and Pinker, 1985; Andersen, 1990; Andersen and Kramer, 1993; Theeuwes et al, 1998; Theeuwes and Pratt, 2003) The latter issue recently received more attention and was addressed by an increasing number of investigations 2012; Chen et al, 2012; Finlayson et al, 2013; Weidner et al, 2014; Finlayson and Grove, 2015; Wang et al, 2015, 2016; Jiang et al, 2016; Papenmeier and Schwan, 2016; Plewan and Rinkenauer, 2016) Some of these studies imply that perceptual mechanisms do not always correspond between 2D and 3D settings. The observed effects were limited to renderings of familiar object stimuli (i.e., a tennis ball compared to plain disks) and in an additional experimental condition without depth and distance information participants’ response behavior was solely affected by retinal object size
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