Individual differences in spatial relation processing: effects of strategy, ability, and gender

Abstract

Numerous studies have focused on the distinction between categorical and coordinate spatial relations. Categorical relations are propositional and abstract, and often related to a left hemisphere advantage. Coordinate relations specify the metric information of the relative locations of objects, and can be linked to right hemisphere processing. Yet, not all studies have reported such a clear double dissociation; in particular the categorical left hemisphere advantage is not always reported. In the current study we investigated whether verbal and spatial strategies, verbal and spatial cognitive abilities, and gender could account for the discrepancies observed in hemispheric lateralization of spatial relations. Seventy-five participants performed two visual half field, match-to-sample tasks (Van der Ham, van Wezel, Oleksiak, & Postma, 2007; Van der Ham, Raemaekers, van Wezel, Oleksiak, and Postma, 2009) to study the lateralization of categorical and coordinate relation processing. For each participant we determined the strategy they used in each of the two tasks. Consistent with previous findings, we found an overall categorical left hemisphere advantage and coordinate right hemisphere advantage. The lateralization pattern was affected selectively by the degree to which participants used a spatial strategy and by none of the other variables (i.e., verbal strategy, cognitive abilities, and gender). Critically, the categorical left hemisphere advantage was observed only for participants that relied strongly on a spatial strategy. This result is another piece of evidence that categorical spatial relation processing relies on spatial and not verbal processes.

Figure 1

All possible dot positions in the stimuli used. The arms of the cross indicate the four quadrants (categorical task) while dots could appear at four different radial distances from the center of the cross (coordinate task). Note that only one dot was visible in a single stimulus.

Figure 2

The sequence of a single trial. Each trial element is depicted with its duration in ms.

Figure 3

The mean lateralization coefficients of (A) ER and (B) RT. Note. Cat=categorical, coo=coordinate, Negative = leftward lateralization, positive = rightward lateralization. Error bars represent standard error of the mean (SEM).

Figure 4

The mean lateralization coefficients of ER values for the (A) high and (B) low spatial strategy groups for both visual fields. Note. Cat=categorical, coo=coordinate, Negative = leftward lateralization, positive = rightward lateralization. Error bars represent standard error of the mean (SEM).