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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 (2010; Experiment 2). Upper panel: time course of a trial. Participants point from the center of the display to the red one of the two targets indicated by the shape cue (here, a square). Middle panel: spatial priming functions for different cuing intervals. Conventions as in Figure 1. Lower panel: response accuracy in the prime identification task plotted against maximum spatial priming effects in the target identification task. Here and in all further figures, error bars denote standard errors of the mean with pure intersubject variance removed (Cousineau, 2005).
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Figure 3: Paradigm and results from Schmidt and Schmidt (2010; Experiment 2). Upper panel: time course of a trial. Participants point from the center of the display to the red one of the two targets indicated by the shape cue (here, a square). Middle panel: spatial priming functions for different cuing intervals. Conventions as in Figure 1. Lower panel: response accuracy in the prime identification task plotted against maximum spatial priming effects in the target identification task. Here and in all further figures, error bars denote standard errors of the mean with pure intersubject variance removed (Cousineau, 2005).

Mentions: Fascinatingly, all aspects of selective attention in the spatial domain can be generalized to selection in the domains of color and shape features. Schmidt and Schmidt (2010) employed the selection-for-action paradigm to study the effects of feature-based attention on priming. Instead of using a precue that would directly point at the relevant pair of stimulus positions, we employed a shape cue that would indicate the shape of the relevant target stimuli (Figure 3, upper panel). Participants were then instructed to point as quickly as possible from the display center to the cued shape of appointed color (e.g., to the red one of the two squares). Findings were very similar to the ones by Schmidt and Seydell (2008), with spatially directed detours indicating that spatial selection had taken place on the basis of feature-based attention. Enhancement of priming effects was optimal at cuing intervals of 500 ms. With the caveats mentioned above, priming functions were consistent with the rapid-chase criteria, even for the shortest SOAs, suggesting that the attentional modulation directly affected feedforward processing of primes and targets (Figure 3, middle panel). Similar results were obtained when the shape and color domains were swapped, i.e., when participants processed a color cue telling them to respond to the cued color stimulus of appointed shape (Schmidt and Schmidt, 2010; Experiment 1).


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 (2010; Experiment 2). Upper panel: time course of a trial. Participants point from the center of the display to the red one of the two targets indicated by the shape cue (here, a square). Middle panel: spatial priming functions for different cuing intervals. Conventions as in Figure 1. Lower panel: response accuracy in the prime identification task plotted against maximum spatial priming effects in the target identification task. Here and in all further figures, error bars denote standard errors of the mean with pure intersubject variance removed (Cousineau, 2005).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Paradigm and results from Schmidt and Schmidt (2010; Experiment 2). Upper panel: time course of a trial. Participants point from the center of the display to the red one of the two targets indicated by the shape cue (here, a square). Middle panel: spatial priming functions for different cuing intervals. Conventions as in Figure 1. Lower panel: response accuracy in the prime identification task plotted against maximum spatial priming effects in the target identification task. Here and in all further figures, error bars denote standard errors of the mean with pure intersubject variance removed (Cousineau, 2005).
Mentions: Fascinatingly, all aspects of selective attention in the spatial domain can be generalized to selection in the domains of color and shape features. Schmidt and Schmidt (2010) employed the selection-for-action paradigm to study the effects of feature-based attention on priming. Instead of using a precue that would directly point at the relevant pair of stimulus positions, we employed a shape cue that would indicate the shape of the relevant target stimuli (Figure 3, upper panel). Participants were then instructed to point as quickly as possible from the display center to the cued shape of appointed color (e.g., to the red one of the two squares). Findings were very similar to the ones by Schmidt and Seydell (2008), with spatially directed detours indicating that spatial selection had taken place on the basis of feature-based attention. Enhancement of priming effects was optimal at cuing intervals of 500 ms. With the caveats mentioned above, priming functions were consistent with the rapid-chase criteria, even for the shortest SOAs, suggesting that the attentional modulation directly affected feedforward processing of primes and targets (Figure 3, middle panel). Similar results were obtained when the shape and color domains were swapped, i.e., when participants processed a color cue telling them to respond to the cued color stimulus of appointed shape (Schmidt and Schmidt, 2010; Experiment 1).

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