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Information processing correlates of a size-contrast illusion.

Gold JM - Front Psychol (2014)

Bottom Line: Perception is often influenced by context.By correlating the noise with observers' classification decisions, we found that the sizes of the surrounding contextual elements had a direct influence on the relative weight observers assigned to regions within and surrounding the central element.Specifically, observers assigned relatively more weight to the surrounding region and less weight to the central region in the presence of smaller surrounding contextual elements.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychological and Brain Sciences, Indiana University, Bloomington IN, USA.

ABSTRACT
Perception is often influenced by context. A well-known class of perceptual context effects is perceptual contrast illusions, in which proximate stimulus regions interact to alter the perception of various stimulus attributes, such as perceived brightness, color and size. Although the phenomenal reality of contrast effects is well documented, in many cases the connection between these illusions and how information is processed by perceptual systems is not well understood. Here, we use noise as a tool to explore the information processing correlates of one such contrast effect: the Ebbinghaus-Titchener size-contrast illusion. In this illusion, the perceived size of a central dot is significantly altered by the sizes of a set of surrounding dots, such that the presence of larger surrounding dots tends to reduce the perceived size of the central dot (and vise versa). In our experiments, we first replicated previous results that have demonstrated the subjective reality of the Ebbinghaus-Titchener illusion. We then used visual noise in a detection task to probe the manner in which observers processed information when experiencing the illusion. By correlating the noise with observers' classification decisions, we found that the sizes of the surrounding contextual elements had a direct influence on the relative weight observers assigned to regions within and surrounding the central element. Specifically, observers assigned relatively more weight to the surrounding region and less weight to the central region in the presence of smaller surrounding contextual elements. These results offer new insights into the connection between the subjective experience of size-contrast illusions and their associated information processing correlates.

No MeSH data available.


Related in: MedlinePlus

Hypothetical stimuli that could be used in an experiment that would involve having observers discriminate between the sizes of the inner circles rather than detecting their presence (see text for details).
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Figure 9: Hypothetical stimuli that could be used in an experiment that would involve having observers discriminate between the sizes of the inner circles rather than detecting their presence (see text for details).

Mentions: Finally, although we chose to use a detection task in our experiments for its relative simplicity, an interesting future direction would be to carry out similar experiments using tasks that might rely more directly upon an observer’s ability to make judgments about relative size. Figure 9 illustrates a task and set of stimuli one might use in such a hypothetical experiment. In this case, an observer would be asked to determine which of two central dots that slightly differ in size had appeared on a given trial, in the presence of either large or small inducing elements. It is possible that such a task would tap more directly into the same underlying processes that lead to the misperception of size associated with the subjective experience of the Ebbinghaus–Titchener illusion. We are currently exploring these and other possibilities.


Information processing correlates of a size-contrast illusion.

Gold JM - Front Psychol (2014)

Hypothetical stimuli that could be used in an experiment that would involve having observers discriminate between the sizes of the inner circles rather than detecting their presence (see text for details).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928540&req=5

Figure 9: Hypothetical stimuli that could be used in an experiment that would involve having observers discriminate between the sizes of the inner circles rather than detecting their presence (see text for details).
Mentions: Finally, although we chose to use a detection task in our experiments for its relative simplicity, an interesting future direction would be to carry out similar experiments using tasks that might rely more directly upon an observer’s ability to make judgments about relative size. Figure 9 illustrates a task and set of stimuli one might use in such a hypothetical experiment. In this case, an observer would be asked to determine which of two central dots that slightly differ in size had appeared on a given trial, in the presence of either large or small inducing elements. It is possible that such a task would tap more directly into the same underlying processes that lead to the misperception of size associated with the subjective experience of the Ebbinghaus–Titchener illusion. We are currently exploring these and other possibilities.

Bottom Line: Perception is often influenced by context.By correlating the noise with observers' classification decisions, we found that the sizes of the surrounding contextual elements had a direct influence on the relative weight observers assigned to regions within and surrounding the central element.Specifically, observers assigned relatively more weight to the surrounding region and less weight to the central region in the presence of smaller surrounding contextual elements.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychological and Brain Sciences, Indiana University, Bloomington IN, USA.

ABSTRACT
Perception is often influenced by context. A well-known class of perceptual context effects is perceptual contrast illusions, in which proximate stimulus regions interact to alter the perception of various stimulus attributes, such as perceived brightness, color and size. Although the phenomenal reality of contrast effects is well documented, in many cases the connection between these illusions and how information is processed by perceptual systems is not well understood. Here, we use noise as a tool to explore the information processing correlates of one such contrast effect: the Ebbinghaus-Titchener size-contrast illusion. In this illusion, the perceived size of a central dot is significantly altered by the sizes of a set of surrounding dots, such that the presence of larger surrounding dots tends to reduce the perceived size of the central dot (and vise versa). In our experiments, we first replicated previous results that have demonstrated the subjective reality of the Ebbinghaus-Titchener illusion. We then used visual noise in a detection task to probe the manner in which observers processed information when experiencing the illusion. By correlating the noise with observers' classification decisions, we found that the sizes of the surrounding contextual elements had a direct influence on the relative weight observers assigned to regions within and surrounding the central element. Specifically, observers assigned relatively more weight to the surrounding region and less weight to the central region in the presence of smaller surrounding contextual elements. These results offer new insights into the connection between the subjective experience of size-contrast illusions and their associated information processing correlates.

No MeSH data available.


Related in: MedlinePlus