The functional architecture of the human body: assessing body representation by sorting body parts and activities

We investigated mental representations of body parts and body-related activities in two subjects with congenitally absent limbs (one with, the other without phantom sensations), a wheelchair sports group of paraplegic participants, and two groups of participants with intact limbs. To analyse mental representation structures, we applied Structure Dimensional Analysis. Verbal labels indicating body parts and related activities were presented in randomized lists that had to be sorted according to a hierarchical splitting paradigm. Participants were required to group the items according to whether or not they were considered related, based on their own body perception. Results of the groups of physically intact and paraplegic participants revealed separate clusters for the lower body, upper body, fingers and head. The participant with congenital phantom limbs also showed a clear separation between upper and lower body (but not between fingers and hands). In the participant without phantom sensations of the absent arms, no such modularity emerged, but the specific practice of his right foot in communication and daily routines was reflected. Sorting verbal labels of body parts and activities appears a useful method to assess body representation in individuals with special body anatomy or function and leads to conclusions largely compatible with other assessment procedures.