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Visual processing in rapid-chase systems: image processing, attention, and awareness.

Schmidt T, Haberkamp A, Veltkamp GM, Weber A, Seydell-Greenwald A, Schmidt F - Front Psychol (2011)

Bottom Line: We propose that response priming captures the output of the first feedforward pass of visual signals through the visuomotor system, and that this output lacks some characteristic features of more elaborate, recurrent processing.This way, visuomotor measures may become dissociated from several aspects of conscious vision.We argue that "fast" visuomotor measures predominantly driven by feedforward processing should supplement "slow" psychophysical measures predominantly based on visual awareness.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Social Sciences, Psychology I, University of Kaiserslautern Kaiserslautern, Germany.

ABSTRACT
Visual stimuli can be classified so rapidly that their analysis may be based on a single sweep of feedforward processing through the visuomotor system. Behavioral criteria for feedforward processing can be evaluated in response priming tasks where speeded pointing or keypress responses are performed toward target stimuli which are preceded by prime stimuli. We apply this method to several classes of complex stimuli. (1) When participants classify natural images into animals or non-animals, the time course of their pointing responses indicates that prime and target signals remain strictly sequential throughout all processing stages, meeting stringent behavioral criteria for feedforward processing (rapid-chase criteria). (2) Such priming effects are boosted by selective visual attention for positions, shapes, and colors, in a way consistent with bottom-up enhancement of visuomotor processing, even when primes cannot be consciously identified. (3) Speeded processing of phobic images is observed in participants specifically fearful of spiders or snakes, suggesting enhancement of feedforward processing by long-term perceptual learning. (4) When the perceived brightness of primes in complex displays is altered by means of illumination or transparency illusions, priming effects in speeded keypress responses can systematically contradict subjective brightness judgments, such that one prime appears brighter than the other but activates motor responses as if it was darker. We propose that response priming captures the output of the first feedforward pass of visual signals through the visuomotor system, and that this output lacks some characteristic features of more elaborate, recurrent processing. This way, visuomotor measures may become dissociated from several aspects of conscious vision. We argue that "fast" visuomotor measures predominantly driven by feedforward processing should supplement "slow" psychophysical measures predominantly based on visual awareness.

No MeSH data available.


Related in: MedlinePlus

Paradigm and results from Schmidt and Schmidt (2009). (A) Time course of a trial. Participants’ task is to point to the image containing an animal, using a hand-held stylus. The arrow illustrates a correct pointing response. (B) Definition of spatial priming effects. Sensor positions in consistent and inconsistent trials were projected onto the target–non-target axis and subtracted. The resulting measure of priming is negative when the sensor position in consistent trials leads the sensor position in inconsistent trials. (C) Spatial priming functions. Only correct responses are shown; functions are locked to prime onset. Reproduced with permission from Psychonomic Society Inc.
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Figure 1: Paradigm and results from Schmidt and Schmidt (2009). (A) Time course of a trial. Participants’ task is to point to the image containing an animal, using a hand-held stylus. The arrow illustrates a correct pointing response. (B) Definition of spatial priming effects. Sensor positions in consistent and inconsistent trials were projected onto the target–non-target axis and subtracted. The resulting measure of priming is negative when the sensor position in consistent trials leads the sensor position in inconsistent trials. (C) Spatial priming functions. Only correct responses are shown; functions are locked to prime onset. Reproduced with permission from Psychonomic Society Inc.

Mentions: Of course, the sheer rapidity of this system is highly suggestive of feedforward processing. But does the system meet the rapid-chase criteria? We employed a primed pointing paradigm featuring natural images, comparing four tasks in two experiments (Schmidt and Schmidt, 2009). In each task, two target images (each from one of two picture categories, e.g., animals and objects) appeared in diagonally opposite quadrants of the display (Figure 1A). Participants pointed from the center of the display toward the picture of the relevant target category (e.g., the animal). Before the targets, two primes appeared at the same positions for 33 ms at prime–target SOAs between 33 and 100 ms. Image categories could either be presented at the same spatial positions in primes as well as targets (consistent trials), or prime categories could be spatially switched with respect to target categories (inconsistent trials). Pointing responses were recorded by a POLHEMUS FASTRAK® magnetic tracking device. Primes in consistent and inconsistent trials were expected to initiate responses toward the direction of the correct target image or the opposite direction, respectively. We employed the following tasks:


Visual processing in rapid-chase systems: image processing, attention, and awareness.

Schmidt T, Haberkamp A, Veltkamp GM, Weber A, Seydell-Greenwald A, Schmidt F - Front Psychol (2011)

Paradigm and results from Schmidt and Schmidt (2009). (A) Time course of a trial. Participants’ task is to point to the image containing an animal, using a hand-held stylus. The arrow illustrates a correct pointing response. (B) Definition of spatial priming effects. Sensor positions in consistent and inconsistent trials were projected onto the target–non-target axis and subtracted. The resulting measure of priming is negative when the sensor position in consistent trials leads the sensor position in inconsistent trials. (C) Spatial priming functions. Only correct responses are shown; functions are locked to prime onset. Reproduced with permission from Psychonomic Society Inc.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3139957&req=5

Figure 1: Paradigm and results from Schmidt and Schmidt (2009). (A) Time course of a trial. Participants’ task is to point to the image containing an animal, using a hand-held stylus. The arrow illustrates a correct pointing response. (B) Definition of spatial priming effects. Sensor positions in consistent and inconsistent trials were projected onto the target–non-target axis and subtracted. The resulting measure of priming is negative when the sensor position in consistent trials leads the sensor position in inconsistent trials. (C) Spatial priming functions. Only correct responses are shown; functions are locked to prime onset. Reproduced with permission from Psychonomic Society Inc.
Mentions: Of course, the sheer rapidity of this system is highly suggestive of feedforward processing. But does the system meet the rapid-chase criteria? We employed a primed pointing paradigm featuring natural images, comparing four tasks in two experiments (Schmidt and Schmidt, 2009). In each task, two target images (each from one of two picture categories, e.g., animals and objects) appeared in diagonally opposite quadrants of the display (Figure 1A). Participants pointed from the center of the display toward the picture of the relevant target category (e.g., the animal). Before the targets, two primes appeared at the same positions for 33 ms at prime–target SOAs between 33 and 100 ms. Image categories could either be presented at the same spatial positions in primes as well as targets (consistent trials), or prime categories could be spatially switched with respect to target categories (inconsistent trials). Pointing responses were recorded by a POLHEMUS FASTRAK® magnetic tracking device. Primes in consistent and inconsistent trials were expected to initiate responses toward the direction of the correct target image or the opposite direction, respectively. We employed the following tasks:

Bottom Line: We propose that response priming captures the output of the first feedforward pass of visual signals through the visuomotor system, and that this output lacks some characteristic features of more elaborate, recurrent processing.This way, visuomotor measures may become dissociated from several aspects of conscious vision.We argue that "fast" visuomotor measures predominantly driven by feedforward processing should supplement "slow" psychophysical measures predominantly based on visual awareness.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Social Sciences, Psychology I, University of Kaiserslautern Kaiserslautern, Germany.

ABSTRACT
Visual stimuli can be classified so rapidly that their analysis may be based on a single sweep of feedforward processing through the visuomotor system. Behavioral criteria for feedforward processing can be evaluated in response priming tasks where speeded pointing or keypress responses are performed toward target stimuli which are preceded by prime stimuli. We apply this method to several classes of complex stimuli. (1) When participants classify natural images into animals or non-animals, the time course of their pointing responses indicates that prime and target signals remain strictly sequential throughout all processing stages, meeting stringent behavioral criteria for feedforward processing (rapid-chase criteria). (2) Such priming effects are boosted by selective visual attention for positions, shapes, and colors, in a way consistent with bottom-up enhancement of visuomotor processing, even when primes cannot be consciously identified. (3) Speeded processing of phobic images is observed in participants specifically fearful of spiders or snakes, suggesting enhancement of feedforward processing by long-term perceptual learning. (4) When the perceived brightness of primes in complex displays is altered by means of illumination or transparency illusions, priming effects in speeded keypress responses can systematically contradict subjective brightness judgments, such that one prime appears brighter than the other but activates motor responses as if it was darker. We propose that response priming captures the output of the first feedforward pass of visual signals through the visuomotor system, and that this output lacks some characteristic features of more elaborate, recurrent processing. This way, visuomotor measures may become dissociated from several aspects of conscious vision. We argue that "fast" visuomotor measures predominantly driven by feedforward processing should supplement "slow" psychophysical measures predominantly based on visual awareness.

No MeSH data available.


Related in: MedlinePlus