Abstract
A reflection between a pair of contours is more rapidly detected than a translation, but this effect is stronger when the contours are closed to form a single object compared to when they are closed to form 2 objects with a gap between them. That is, grouping changes the relative salience of different regularities. We tested whether this manipulation would also change preference for reflection or translation. We measured preference for these patterns using the Implicit Association Test (IAT). On some trials, participants saw words that were either positive or negative and had to classify them as quickly as possible. On interleaved trials, they saw reflection or translation patterns and again had to classify them. Participants were faster when 1 button was used for reflection and positive words and another button was used for translation and negative words, compared to when the reverse response mapping was used (translation and positive vs. reflection and negative). This reaction time difference indicates an implicit preference for reflection over translation. However, the size of the implicit preference was significantly reduced in the Two-objects condition. We concluded that factors that affect perceptual sensitivity also systematically affect implicit preference formation.
Highlights
The environment is full of symmetrical objects at all scales, and the visual systems of many animals are tuned to process symmetry efficiently, possibly because it is a valid cue for figure-ground segmentation or because it indicates the presence of other animals
Participants were faster when 1 button was used for reflection and positive words and another button was used for translation and negative words, compared to when the reverse response mapping was used
In previous work we reported implicit preference for reflection over translation using the Implicit Association Test (IAT) (Makin, Pecchinenda, & Bertamini, in press), but in this study, we focus on the role of grouping
Summary
The environment is full of symmetrical objects at all scales, and the visual systems of many animals are tuned to process symmetry efficiently, possibly because it is a valid cue for figure-ground segmentation or because it indicates the presence of other animals (for reviews, see Treder, 2010; Tyler, 1995; Wagemans, 1995). Symmetrical patterns are produced by transformations that preserve the metric structure of the pattern. In the plane, these transformations are reflection, translation, rotation and glide reflection (Palmer, 1991; Wagemans, 1995). These transformations are reflection, translation, rotation and glide reflection (Palmer, 1991; Wagemans, 1995) These patterns are regular, some are more salient for the human visual system. Over 100 years ago, Ernst Mach noticed that bilateral reflectional symmetry is most detected, when the axis of reflection is vertical (Mach, 1886/1959). The perceptual advantage for vertical reflection has subsequently been confirmed by many psychophysical studies, most measuring reaction times (Palmer & Hemenway, 1978; Royer, 1981; Wenderoth, 1994)
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