Mental images of mental maps

People who readily report having mental images describe the experience as being similar to seeing a picture – a picture in the head so speak. Furthermore, they claim to be able to inspect these images and read off information in the same way that they are able to inspect a physical picture and read off information from the picture. How many legs has the Eiffel Tower – well inspect your mental image. To make any progress in understanding what might be going on, we need to be clear about what constitutes a picture. In sense a picture shows what the world is like - it depicts something in the world. A photograph of the Eiffel Tower shows it as it is.

We would also say that a picture provides a particular view of the world. We see the front of the Mona Lisa’s face not the back. Finally a picture has certain geometric properties. The Eiffel Tower is long and thin as it is in the photograph. For cognitive psychologists the key questions have been to what extent do mental images share these kind of picture properties. We will concentrate on the claim that mental images capture spatial relations in the same way that a photograph does. In one classic experiment participants were provided with a cartoon of a map of desert island. Clearly marked on the map were the locations of key landmarks a sandy bay, a well, a lighthouse, and so on.

Participants were told to learn the map and commit it to memory and their memory for the map was tested by having them draw it. Once their drawings were good likenesses to the map then their ability to image the map and recover information from it was tapped. Participants were told to image the map and focus on a named landmark. They were then provided with the name of another possible landmark and if they decided that the name landmark was on the map they had to scan their image by moving a spotlight between the two named locations and respond once they arrived at the destination.

The data were clear cut in showing that the participants response times varied directly with the distance between the landmarks on the map. That is landmarks close together were responded to quicker than were landmarks far apart. This evidence has been used to support the claim that images have spatial properties – they preserve the geometric relations of the thing being imagined. More generally, this sort of evidence has been used to bolster the claim that images are like pictures in the head – mental images have spatial properties in the same way that pictures do. Much controversy has raged over whether or not such conclusions necessarily follow from the data. Before we expose alternative interpretations you might consider what else might be going on.