Have a Good Grasp of the Worldthe World

Study on the Links Between Action and Perception in Schizophrenia, " Have a Good Grasp of the World "

Brief Summary: In schizophrenia, dislocation of psychic functions involving a loss of contact with reality is frequently found. A fragmentation of motor and sensory perceptions could be held responsible. However, automatic integration between perception and action is the necessary condition to be in "relationship with the world." Affordance is the experimental link between object perception and potentially associated actions (Gibson, 1977, 1979) explored by Stimulus Response Compatibility (SRC) paradigm. With Tucker & Ellis sensory motor compatibility task (1998), with a modified response device (responses given with grasp), we study the impact of motor activation on these affordance effects. In this study, a group of controls will also be included in order to understand, as precisely as possible, the mechanisms involved (i.e., interference between the perception of the object and the response gesture).

Schizophrenic patients will perform: Alert TEA, (Zimmermann and Fimm, 2005), Edinburgh laterality questionnaire (Oldfield, 1971), IQ test (IQ: PM38, Raven, 1960), and the PANSS (Positive and Negative Syndrome Scale, Kay et al., 1987). Controls will only perform the laterality questionnaire. Then all will perform the affordance task, in which photographs of 20 objects of everyday life, typically graspable with one hand, are presented in 4 orientations. Participants have to respond in a graspable device, as quickly as possible, if the object is presented upright or inverted.

Inclusion Criteria:

• For patients:

  • a DSM-IV diagnosis of schizophrenia (men or women),
  • no change in antipsychotic medication and clinical status within four weeks prior to the study

• For patients and control group • Age ≥ 18 years et ≤ 55 years

Exclusion Criteria:

• History of head trauma,
• neurological disease with cerebral repercussion or not stabilized serious physical illness;
• psychotropic medication
• disorders related to the use of a psychoactive substance (abuse, dependence or withdrawal);

Exclusion Criteria:

• For patients:

  • IQ < 70

• For patients and control group

  • History of head trauma,
  • neurological disease with cerebral repercussion or not stabilized serious physical illness;
  • psychotropic medication
  • disorders related to the use of a psychoactive substance (abuse, dependence or withdrawal);