Activation of response force by self-splitting objects: Where are the limits of feedforward Gestalt processing?

Vancleef

2016

Vision Research

In contour integration, increased difficulty in detection and shape discrimination of a chain of parallel elements (a ladder contour) compared to collinear elements (a snake contour) suggests more extensive processing of ladders than of snakes. In addition, conceptual similarities between ladders and textures - which also involve grouping of parallel elements - raises the question whether ladder and texture processing requires feedback from higher visual areas while snakes are processed in a fast feedforward sweep. We tested this in a response priming paradigm, where participants responded as quickly and accurately as possible to the orientation of a diagonal contour in a Gabor array (target). The diagonal was defined either by a snake, ladder, texture, or a continuous line. The target was preceded with varying stimulus onset asynchrony (SOA) by a prime that was either a snake, ladder, or texture, and was consistent or inconsistent to the response demands of the target. Resulting priming effects clearly distinguished between processing of snakes, ladders, and textures. Effects generally increased with SOA but were stronger for snakes and textures compared to ladders. Importantly, only priming effects for snakes were fully present already in the fastest response times, in accordance with a simple feedforward processing model. We conclude that snakes, ladders, and textures do not share similar processing characteristics, with snakes exhibiting a pronounced processing advantage.

Section: Discussionsupporting

confidence: 71%

Response priming evidence for feedforward processing of snake contours but not of ladder contours and textures

Vancleef

2016

Vision Research

“…The same pattern of sequential response activation can be observed in overt response behavior, such as the kinematics of primed pointing responses (Brenner & Smeets, 2004;T. Schmidt, 2002) or the time course of force deployment in isometric buttonpresses (F. Schmidt, Weber, & Schmidt, 2014). These studies have shown that inconsistent primes are able to mislead pointing movements in the wrong direction, such that the initial behavioral response is time-locked to the prime, first proceeds in the direction specified by the prime, and only then proceeds in the target direction (F. T.…”

Section: Motor Activation In Response Primingmentioning

confidence: 73%

Mask-triggered thrust reversal in the negative compatibility effect

Hauch

Atten Percept Psychophys

2015

Rapid motor responses to visual stimuli can involve both the activation and inhibition of motor responses. Here, we trace the early processing dynamics of response generation, examining whether activation and inhibition events form a strict sequence when elicited by sequential stimuli, as we would expect if motor events are driven by fast, stimulustriggered feedforward sweeps. We employed identical stimuli in two complementary paradigms. In response priming, responses to a target stimulus are speeded or slowed by a masked prime triggering the same or an alternative response, respectively. By prolonging the prime-target interval, the response-priming effect can reverse to form the negative compatibility effect (NCE), especially when the mask contains response-relevant features. We report two experiments in which primed pointing movements going in ten possible directions were measured with response-relevant, response-irrelevant, or no masks interleaved between the primes and targets, while selective visual attention was varied. We showed that in response priming, initial responses are controlled exclusively by the prime. In the NCE, however, even the earliest movement phase is controlled jointly by the prime, mask, and target information, and a massive force in counterdirection to the primed response reverses the priming effects specifically for slow responses. We conclude that response priming reflects a strict sequence of feedforward response activations, whereas the activation/inhibition events in the NCE are not strictly serial, but integrate information from the different stimuli over time. Even though the mask features and visual attention modulate the NCE, its major source is a mask-induced, direction-specific thrust reversal of the initial response.

“…Generally, response priming effects occur because the prime activates the response assigned to it. This has been shown early on in the time course of lateralized readiness potentials (e.g., Klotz, Heumann, Ansorge & Neumann, 2007) as well as in online measurements of pointing or force responses (e.g., Schmidt, Niehaus & Nagel, 2006b;Schmidt, Weber & Schmidt, 2014). Response priming has not only been demonstrated for basic features such as color or shape, but also for complex figural features such as closure and symmetry (Schmidt & Schmidt, 2013).…”

Section: Response Priming As a Tool To Investigate The Time Course Ofmentioning

confidence: 90%

Temporal processing characteristics of the Ponzo illusion

Haberkamp

2015

Psychological Research

Many visual illusions result from assumptions of our visual system that are based on its long-term adaptation to our visual environment. Thus, visual illusions provide the opportunity to identify and learn about these fundamental assumptions. In this paper, we investigate the Ponzo illusion. Although many previous studies researched visual processing of the Ponzo illusion, only very few considered temporal processing aspects. However, it is well known that our visual percept is modulated by temporal factors. First, we used the Ponzo illusion as prime in a response priming task to test whether it modulates subsequent responses to the longer (or shorter) of two target bars. Second, we used the same stimuli in a perceptual task to test whether the Ponzo illusion is effective for very short presentation times (12 ms). We observed considerable priming effects that were of similar magnitude as those of a control condition. Moreover, the variations in the priming effects as a function of prime-target stimulus-onset asynchrony were very similar to that of the control condition. However, when analyzing priming effects as a function of participants' response speed, effects for the Ponzo illusion increased in slower responses. We conclude that although the illusion is established rapidly within the visual system, the full integration of context information is based on more time-consuming and later visual processing.