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Parietal lesions produce illusory conjunction errors in rats.

Kesner RP - Front Integr Neurosci (2012)

Bottom Line: Illusory-conjunction errors result when an object is correctly identified but is combined incorrectly.Based on a subsequent error analysis for color and size, the results showed a significant increase in illusory conjunction errors for the PC lesioned rats relative to controls for color and relative to color discrimination, suggesting that the PC may support feature binding as it relates to color.There was an increase in illusory conjunctions errors for both the PC lesioned and control animals for size, but this appeared to be due to highly variable performance with size discrimination.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Utah, Salt Lake City UT, USA.

ABSTRACT
When several different objects are presented, visual objects are perceived correctly only if their features are identified and then bound together. Illusory-conjunction errors result when an object is correctly identified but is combined incorrectly. The parietal cortex (PC) has been shown repeatedly to play an important role in feature binding. The present study builds on a series of recent studies that have made use of visual search paradigms to elucidate the neural system involved in feature binding. This experiment attempts to define the role the PC plays in binding the properties of a visual object that varies on the features of color and size in rats. Rats with PC lesions or control surgery were exposed to three blocks of 20 trials administered over a 1-week period, with each block containing 10-one feature and 10-two feature trials. The target object consisted of one color object (e.g., black and white) and one size object (e.g., short and tall). Of the 10 one feature trials, five of the trials were tailored specifically for size discrimination and five for color discrimination. In the two-feature condition, the animal was required to locate the targeted object among four objects with two objects differing in size and two objects differing in color. The results showed that the PC lesioned compared to control rats had difficulty in learning the one and two features components of the task and the rats also performed more poorly on the one vs. two feature components of the task. Based on a subsequent error analysis for color and size, the results showed a significant increase in illusory conjunction errors for the PC lesioned rats relative to controls for color and relative to color discrimination, suggesting that the PC may support feature binding as it relates to color. There was an increase in illusory conjunctions errors for both the PC lesioned and control animals for size, but this appeared to be due to highly variable performance with size discrimination. Overall these results suggest that the PC rats display performance errors that appear to be consistent with the notion of illusory conjunction errors.

No MeSH data available.


Related in: MedlinePlus

Mean number of search errors for one or two features for object color for control and parietal cortex lesioned rats as a function of blocks of trials. Each block consisted of 20 trials.
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Figure 3: Mean number of search errors for one or two features for object color for control and parietal cortex lesioned rats as a function of blocks of trials. Each block consisted of 20 trials.

Mentions: To analyze further whether the errors were either based on problems with size or color discrimination, the data were analyzed in terms of mean total number of color or size errors across blocks of trials for the one- and two-feature conditions. The results for mean number of errors for color are shown in Figure 3 and indicate that for the control rats the mean total number of errors decreased across blocks of trials for both the one- and two-feature condition. For the first block the PC lesioned rats displayed a high mean total number of errors for the two-feature condition relative to the one-feature condition and for the one- and two-feature conditions for the control group. For the third block of trials the PC lesioned rats displayed a high mean total number of errors in both the one- and two-feature conditions relative to the control one- and two-feature conditions. The analysis revealed a significant group effect [F(1, 10) = 25.4, p < 0.0005], a significant blocks of trials effect [F(2, 20) = 10.14, p = 0.0009], a significant feature effect [F(1, 10) = 5.1, p = 0.047], and a significant interaction between groups, blocks of trials, and features [F(2, 20) = 4.3, p = 0.028]. A subsequent Newman–Keuls test for the interaction effect revealed that for the first block the PC lesioned rats displayed a significantly higher mean total number of errors for the two-feature condition relative to the one-feature condition and for the one- and two-feature conditions for the control group (p < 0.01). For the third block of trials the PC lesioned rats displayed a significantly higher mean total number of errors in both the one- and two-feature conditions relative to the control one- and two-feature conditions (p < 0.05). The results for color errors indicate that PC lesioned rats relative to controls made only a few errors in detecting the one feature component of the task, but they made many errors throughout all three blocks of trials for the two-feature condition suggesting the appearance of illusory conjunction errors.


Parietal lesions produce illusory conjunction errors in rats.

Kesner RP - Front Integr Neurosci (2012)

Mean number of search errors for one or two features for object color for control and parietal cortex lesioned rats as a function of blocks of trials. Each block consisted of 20 trials.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3351790&req=5

Figure 3: Mean number of search errors for one or two features for object color for control and parietal cortex lesioned rats as a function of blocks of trials. Each block consisted of 20 trials.
Mentions: To analyze further whether the errors were either based on problems with size or color discrimination, the data were analyzed in terms of mean total number of color or size errors across blocks of trials for the one- and two-feature conditions. The results for mean number of errors for color are shown in Figure 3 and indicate that for the control rats the mean total number of errors decreased across blocks of trials for both the one- and two-feature condition. For the first block the PC lesioned rats displayed a high mean total number of errors for the two-feature condition relative to the one-feature condition and for the one- and two-feature conditions for the control group. For the third block of trials the PC lesioned rats displayed a high mean total number of errors in both the one- and two-feature conditions relative to the control one- and two-feature conditions. The analysis revealed a significant group effect [F(1, 10) = 25.4, p < 0.0005], a significant blocks of trials effect [F(2, 20) = 10.14, p = 0.0009], a significant feature effect [F(1, 10) = 5.1, p = 0.047], and a significant interaction between groups, blocks of trials, and features [F(2, 20) = 4.3, p = 0.028]. A subsequent Newman–Keuls test for the interaction effect revealed that for the first block the PC lesioned rats displayed a significantly higher mean total number of errors for the two-feature condition relative to the one-feature condition and for the one- and two-feature conditions for the control group (p < 0.01). For the third block of trials the PC lesioned rats displayed a significantly higher mean total number of errors in both the one- and two-feature conditions relative to the control one- and two-feature conditions (p < 0.05). The results for color errors indicate that PC lesioned rats relative to controls made only a few errors in detecting the one feature component of the task, but they made many errors throughout all three blocks of trials for the two-feature condition suggesting the appearance of illusory conjunction errors.

Bottom Line: Illusory-conjunction errors result when an object is correctly identified but is combined incorrectly.Based on a subsequent error analysis for color and size, the results showed a significant increase in illusory conjunction errors for the PC lesioned rats relative to controls for color and relative to color discrimination, suggesting that the PC may support feature binding as it relates to color.There was an increase in illusory conjunctions errors for both the PC lesioned and control animals for size, but this appeared to be due to highly variable performance with size discrimination.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Utah, Salt Lake City UT, USA.

ABSTRACT
When several different objects are presented, visual objects are perceived correctly only if their features are identified and then bound together. Illusory-conjunction errors result when an object is correctly identified but is combined incorrectly. The parietal cortex (PC) has been shown repeatedly to play an important role in feature binding. The present study builds on a series of recent studies that have made use of visual search paradigms to elucidate the neural system involved in feature binding. This experiment attempts to define the role the PC plays in binding the properties of a visual object that varies on the features of color and size in rats. Rats with PC lesions or control surgery were exposed to three blocks of 20 trials administered over a 1-week period, with each block containing 10-one feature and 10-two feature trials. The target object consisted of one color object (e.g., black and white) and one size object (e.g., short and tall). Of the 10 one feature trials, five of the trials were tailored specifically for size discrimination and five for color discrimination. In the two-feature condition, the animal was required to locate the targeted object among four objects with two objects differing in size and two objects differing in color. The results showed that the PC lesioned compared to control rats had difficulty in learning the one and two features components of the task and the rats also performed more poorly on the one vs. two feature components of the task. Based on a subsequent error analysis for color and size, the results showed a significant increase in illusory conjunction errors for the PC lesioned rats relative to controls for color and relative to color discrimination, suggesting that the PC may support feature binding as it relates to color. There was an increase in illusory conjunctions errors for both the PC lesioned and control animals for size, but this appeared to be due to highly variable performance with size discrimination. Overall these results suggest that the PC rats display performance errors that appear to be consistent with the notion of illusory conjunction errors.

No MeSH data available.


Related in: MedlinePlus