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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

Mean adjusted size matches for six new observers and the data combined across all observers under the same conditions as in Experiment 1 (A) and Experiment 2 (B). Error bars correspond to ±2 standard errors of the mean.
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Figure 8: Mean adjusted size matches for six new observers and the data combined across all observers under the same conditions as in Experiment 1 (A) and Experiment 2 (B). Error bars correspond to ±2 standard errors of the mean.

Mentions: The results of this subjective rating experiment are shown in Figure 8. Figure 8A shows the results for the conditions that are the same as Experiment 1 (i.e., high contrast stimuli with no added noise). All observers exhibited the characteristic effect of judging the central dot to be relatively greater in size in the context of small than large inducers, and four of the six observers judged the size of the central dot to fall somewhere in between in the absence of inducers. A one-way repeated measures ANOVA revealed a significant effect of condition [F(2,5) = 12.53, p < 0.01]. Post hoc comparisons using the Tukey HSD test indicated that the mean estimates were significantly greater in the Small Inducers condition than the Large Inducers condition (p < 0.01) as well as the No Inducers condition (p < 0.05), with no significant difference between the Large Inducers and No Inducers conditions.


Information processing correlates of a size-contrast illusion.

Gold JM - Front Psychol (2014)

Mean adjusted size matches for six new observers and the data combined across all observers under the same conditions as in Experiment 1 (A) and Experiment 2 (B). Error bars correspond to ±2 standard errors of the mean.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: Mean adjusted size matches for six new observers and the data combined across all observers under the same conditions as in Experiment 1 (A) and Experiment 2 (B). Error bars correspond to ±2 standard errors of the mean.
Mentions: The results of this subjective rating experiment are shown in Figure 8. Figure 8A shows the results for the conditions that are the same as Experiment 1 (i.e., high contrast stimuli with no added noise). All observers exhibited the characteristic effect of judging the central dot to be relatively greater in size in the context of small than large inducers, and four of the six observers judged the size of the central dot to fall somewhere in between in the absence of inducers. A one-way repeated measures ANOVA revealed a significant effect of condition [F(2,5) = 12.53, p < 0.01]. Post hoc comparisons using the Tukey HSD test indicated that the mean estimates were significantly greater in the Small Inducers condition than the Large Inducers condition (p < 0.01) as well as the No Inducers condition (p < 0.05), with no significant difference between the Large Inducers and No Inducers conditions.

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