Size Isn't All that Matters: Noticing Differences in Size and Temporal Order

Abstract

The ability to represent time and size is essential for thought and action. These domains have traditionally been investigated independently. However, the processing of events in time and space is postulated to have considerable anatomical and behavioral overlap. Here we formally tested for associations and dissociations of abilities in these domains. We examined patterns of impairments in temporal order and relative size judgments in 40 patients with unilateral brain lesions and 20 age-matched control participants. While brain damage can impair both size and temporal order judgments (TOJ), we did not find evidence for global hemispheric differences. When patients were analyzed individually compared to control subjects, we found double dissociations in performances on both kinds of judgments. Voxel lesion symptom mapping allowed us to investigate shared and unique contributions of brain damage to deficits in judgments noticing differences in temporal order and in spatial extent. We found that size and temporal order estimations have overlapping cortical vulnerabilities within the left inferior frontal gyrus, left superior temporal cortex, and bilateral inferior parietal lobule. However, vulnerability unique to TOJ occurred with damage predominantly in left lateralized regions involving inferior and middle frontal cortex and inferior parietal lobule. Conversely, vulnerability unique to size judgments occurred with damage predominantly in right lateralized regions in the supramarginal gyrus and superior temporal cortex. These data provide evidence for interactions between the processing of spatial extent and temporal order; however, they do not provide evidence for right lateralized systems.

Keywords: inferior parietal lobule; size perception; temporal order judgment; temporal perception; voxel lesion symptom mapping.

Figure 1

(A) Size judgment task. Four different areas (104, 108, 110, 113% of standard) (B) Temporal order judgment task. Four temporal offsets (40, 53, 67, 80 ms).

Figure 2

Group-wise Behavioral Results. (A) Performance of left hemisphere involvement, right hemisphere involvement and age-matched participants on size judgment task and (B) Performance of left hemisphere involvement, right hemisphere involvement and age-matched participants on TOJ.

Figure 3

Plots of TOJ versus Size Judgment performance for (A) age-matched controls and (B) patient participants.

Figure 4

Example of two cases that provide evidence of a double dissociation between performance on (A) size judgment and (B) TOJ performance.

Figure 5

Statistical maps of neuroanatomic regions in which damage correlated significantly (using permutation statistics) with (A) impairment on size discrimination and (B) temporal order discrimination.

Figure 6

Statistical maps of neuroanatomic regions in which damage correlated significantly (using permutation statistics) with (A) residuals resulting from size performance regressed against TOJ performance, representing regions where lesions correlate with variance associated with size performance independent of TOJ performance and (B) residuals resulting from TOJ performance regressed against size performance representing regions where lesions correlate with variance associated with TOJ performance independent of size performance.