Assessing the symbolic distance effect in mental images constructed from verbal descriptions: a study of individual differences in the mental comparison of distances.

In two experiments, undergraduates processed a verbal description of a spatial configuration on the periphery of which six landmarks were located. The participants were then invited to generate visual images of the configuration, and to visualize the distances between pairs of landmarks. Their task consisted of deciding which of the two specified distances was longer. The results showed that as the magnitude of the differences in distance increased, the frequency of correct responses was higher, and response times were shorter. This pattern of results is characteristic of the symbolic distance effect, which is especially interesting in the present experiment where the images generated by the participants were constructed after processing a verbal description (rather than reconstructed from previous perceptual experience). In order to assess the role of visual imagery in the comparison of distances, the performance of participants with the highest scores on a visuo-spatial test (the Minnesota Paper Form Board) was compared to that of those with the lowest scores. High visuo-spatial imagers had higher frequencies of correct responses and shorter response times than the low imagers in the distance-comparison task. They outperformed their counterparts even more clearly on the items where the distance differences were the smallest, suggesting that visual imagery is especially important for items requiring the most attentive examination of a visual image. These data are interpreted as reflecting the fact that visual imagery mediates the process of mentally comparing distances, even when learning has been essentially based on verbal input. These findings support the view that a representation constructed from a verbal description may incorporate metric information about distances, and they offer evidence suggesting that visual images constructed from descriptive texts have genuine analog properties.