Rapid processing of closure and viewpoint-invariant symmetry: behavioral criteria for feedforward processing

Abstract

To pin down the processing characteristics of symmetry and closure in contour processing, we investigated their ability to activate rapid motor responses in a primed flanker task. In three experiments, participants selected as quickly and accurately as possible the one of two target contours possessing symmetry or closure. Target pairs were preceded by prime pairs whose spatial arrangement was consistent or inconsistent with respect to the required response. We tested for the efficiency and automaticity of symmetry and closure processing. For both cues, priming effects were present in full magnitude in the fastest motor responses consistent with a simple feedforward model. Priming effects from symmetry cues were independent of skewing and the orientation of their symmetry axis but sometimes failed to increase with increasing prime-target interval. We conclude that closure and (possibly) viewpoint-independent symmetry cues are extracted rapidly during the first feedforward wave of neuronal processing.

Visual Awareness Is Essential for Grouping Based on Mirror Symmetry

“…Importantly, participants were faster in the congruent condition than the incongruent condition (540.15 ms vs. 517.60 ms), indicating response priming. This result is in correspondence with a previous study demonstrating that stimuli with a single vertical axis of symmetry can produce a robust response priming effect when visible [6]. Although the target and congruency did not interact, we examined the effect of congruency for each target.…”

“…Humans are highly sensitive to symmetry [1,2]. Symmetry, which is detected very quickly even in the presence of noise [3][4][5][6], is frequently a salient aspect of form perception, and it plays a role in figural goodness [7,8] and object recognition [9,10].…”

“…To the best of our knowledge, there is no empirical study directly addressing this question. Some researchers have taken the fast and seemingly effortless perception of symmetry as suggesting that symmetry processing can occur without visual awareness, confounding attention and awareness, such as in [6] (see [16] for a review). The relationship between attention and consciousness, which has been a matter of lively debate in the last two decades, is beyond the scope of this paper.…”

Dissociating early and late visual processing via the Ebbinghaus illusion

“…A pair of primes at the center of the screen was succeeded by a pair of fl anking targets ( Fig. 2 ; Schmidt & Schmidt, 2014 ). Participants responded as quickly and accurately as possible whether the small (half of participants: large) target disc was on the left or right side of the display by pressing a left or right button, respectively.…”

Image symmetries: The right balance between evenness and perception

“…The performance of the aforementioned algorithms can be hampered by not taking into account human perception, since it is impossible to neglect those perception mechanisms employed by the human brain when engaging in object recognition tasks [13] [14]. In particular, symmetry detection is just one of the many tool employed during object recognition by humans [15] [16], although it is still unclear how and when symmetry comes into play [17]. Of course, symmetry is a very simple stimulus and it appears that a subconscious process is able to directly detect symmetric patterns in retinal frontoparallel images using some kind of 2D correlation [18].…”