The temporo-parietal junction contributes to global gestalt perception-evidence from studies in chess experts

Abstract

In a recent neuroimaging study the comparison of intact vs. disturbed perception of global gestalt indicated a significant role of the temporo-parietal junction (TPJ) in the intact perception of global gestalt (Huberle and Karnath, 2012). This location corresponded well with the areas known to be damaged or impaired in patients with simultanagnosia after stroke or due to neurodegenerative diseases. It was concluded that the TPJ plays an important role in the integration of individual items to a holistic percept. Thus, increased BOLD signals should be found in this region whenever a task calls for the integration of multiple visual items. Behavioral experiments in chess experts suggested that their superior skills in comparison to chess novices are partly based on fast holistic processing of chess positions with multiple pieces. We thus analyzed BOLD data from four fMRI studies that compared chess experts with chess novices during the presentation of complex chess-related visual stimuli (Bilalić et al., 2010, 2011a,b, 2012). Three regions of interests were defined by significant TPJ clusters in the abovementioned study of global gestalt perception (Huberle and Karnath, 2012) and BOLD signal amplitudes in these regions were compared between chess experts and novices. These cross-paradigm ROI analyses revealed higher signals at the TPJ in chess experts in comparison to novices during presentations of complex chess positions. This difference was consistent across the different tasks in five independent experiments. Our results confirm the assumption that the TPJ region identified in previous work on global gestalt perception plays an important role in the processing of complex visual stimulus configurations.

Keywords: chess; expertise; fMRI; gestalt perception; object perception; simultanagnosia; temporo-parietal junction; visual grouping.

Figure 1

Stimuli applied in the different experiments. (A) Illustration of the global stimuli used in the experiment of Huberle and Karnath (2012). The pictures show two 20% scrambled global objects (circle, square; intact global perception) and one 80% scrambled global object (disturbed global perception). (B) Stimuli used in Experiment 1 (Bilalić et al., 2011b). Pictures of full-board chess positions or faces were presented upright or inverted. Participants had to indicate whether the currently presented stimulus matched the previously presented stimulus. (C) Stimuli of Experiment 2 (Bilalić et al., 2011a). The stimuli were presented on a 3 × 3 miniature chess board. In the check task participants indicated whether the black piece (knight or rook) gives the white king check. In the identity task participants indicated whether the presented black piece is a rook or a knight. In the control task participants identified geometrical shapes (square or diamond). (D) Stimuli of Experiment 3 (Bilalić et al., 2011b). Pictures of full-board chess positions were presented. Participants had to indicate whether the white king was in check in the check task, whether there were knights of both colors presented in the knight task, or whether two dots (black and white) were present in the control (dot) task. (E) Stimuli of Experiment 4 (Bilalić et al., 2010, 2012). Pictures of full-board chess positions were presented. Participants had to indicate whether the number of black threats (how many times black can take white) was four in the threat condition, whether the number of knights and bishops was four in the knights and bishops task and whether the number of all pieces on the board was 15 in the control task. In all three tasks of Experiments 3 and 4, there were two types of positions: normal (taken from chess games of masters) and random (pieces were randomly distributed on the board).

Figure 2

Regions of interests (ROIs) derived from Huberle and Karnath (2012). ROIs were identified as those voxels that showed significantly higher BOLD signals for 20%-scrambled objects (intact global perception) compared to 80%-scrambled objects (disturbed global perception) based on a voxel-level threshold of p < 0.001 (uncorr.). The green color indicates the right TPJ ROI, red describes the left anterior TPJ ROI, blue indicates the left posterior TPJ ROI. ROIs are presented on a 3D rendered surface and axial slices for the left and right hemisphere. MNI coordinates of the center of mass and size of every ROI in mm³ is denoted in the corresponding color.

Figure 3

Results Experiment 1. Percent signal change (PSC) for the two experimental conditions chess and faces (normal and inverted presentation) for experts and novices. Subjects had to indicate whether the currently presented stimulus matched the previously presented stimulus. Results are presented for TPJ ROI right (A), left anterior (B) and left posterior TPJ (C). Error bars indicate standard error of the mean.

Figure 4

Results Experiment 2. Percent signal change (PSC) for the three experimental conditions check (indicate if knight is in check), identity (recognition of a chess piece), and control (recognition of a geometrical shape) for experts and novices in TPJ ROI right (A), left anterior (B), and left posterior TPJ (C). Error bars indicate standard error of the mean.

Figure 5

Results Experiment 3. Percent signal change (PSC) for the three experimental conditions check (recognizing if the white king is in check), knight (recognizing if black/white knights are present), and control (recognizing if a black/white dot is presented) for experts and novices in normal (chess pieces arranged according to real chess matches) and random (chess pieces in randomized distribution) chess arrays. Results are presented for TPJ ROI right (A), left anterior (B), and left posterior TPJ (C). Error bars indicate standard error of the mean.

Figure 6

Results Experiment 4. Percent signal change (PSC) for the three experimental conditions threats (indicated whether the number of threats of black to white was four), knights and bishops (indicate whether the number of knights and bishops of both colors was four), and control (non-chess control task, all pieces regardless of color or type were counted, indicate if the number is 15) for experts and novices in normal (chess pieces arranged according to real chess matches) and random (chess pieces in randomized distribution) chess arrays. Results are presented for TPJ ROI right (A), left anterior (B), and left posterior TPJ (C). Error bars indicate standard error of the mean.