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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 in each condition from Experiment 1. Error bars correspond to ±2 standard errors of the mean.
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Figure 2: Mean adjusted size matches in each condition from Experiment 1. Error bars correspond to ±2 standard errors of the mean.

Mentions: The purpose of Experiment 1 was to verify the presence and measure the magnitude of the subjective size-contrast illusion produced by the Ebbinghaus–Titchener patterns shown in Figure 1. Three observers repeatedly adjusted an isolated circle to match the perceived size of the central dot in each stimulus condition. The mean adjusted matching sizes for each observer as well as the mean values across observers are shown in Figure 2. These data show there was a consistent effect of the presence of the inducers, with Large Inducers producing smaller estimates than Small Inducers and No Inducers falling in between. A one-way repeated measures ANOVA revealed a significant effect of condition [F(2,2) = 7.74, p < 0.05]. Post hoc comparisons using the Tukey HSD test indicated that the mean estimate in the Small Inducers condition was significantly greater than the mean estimate in the Large Inducers condition (p < 0.05). There were no significant differences between the mean estimates in the No Inducers condition and either the Small or Large Inducers conditions. Thus, Experiment 1 established that our stimuli produced significant size-contrast illusions for all three of our observers.


Information processing correlates of a size-contrast illusion.

Gold JM - Front Psychol (2014)

Mean adjusted size matches in each condition from Experiment 1. 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 2: Mean adjusted size matches in each condition from Experiment 1. Error bars correspond to ±2 standard errors of the mean.
Mentions: The purpose of Experiment 1 was to verify the presence and measure the magnitude of the subjective size-contrast illusion produced by the Ebbinghaus–Titchener patterns shown in Figure 1. Three observers repeatedly adjusted an isolated circle to match the perceived size of the central dot in each stimulus condition. The mean adjusted matching sizes for each observer as well as the mean values across observers are shown in Figure 2. These data show there was a consistent effect of the presence of the inducers, with Large Inducers producing smaller estimates than Small Inducers and No Inducers falling in between. A one-way repeated measures ANOVA revealed a significant effect of condition [F(2,2) = 7.74, p < 0.05]. Post hoc comparisons using the Tukey HSD test indicated that the mean estimate in the Small Inducers condition was significantly greater than the mean estimate in the Large Inducers condition (p < 0.05). There were no significant differences between the mean estimates in the No Inducers condition and either the Small or Large Inducers conditions. Thus, Experiment 1 established that our stimuli produced significant size-contrast illusions for all three of our observers.

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