Three key schizophrenic deficits

1. disorder of willed action
2. disorder of self-monitoring
3. disorder of monitoring the intentions of others

Defects in Willed Action

Norman & Shallice’s model of the control of action has 2 central components

1. Contention Scheduling is a collection of routinized and overlearned action sequences that compete for expression and can lead to action
2. The Supervisory Attentional System exerts its influence by biasing the activation of action sequences at the level of contention scheduling. Thus, the SAS can inhibit stimulus-driven activities, it can terminate action sequences in progress, and can generate its own actions by increasing the activation of action sequences which will then find expression.

• Positive signs are the result of action sequences elicited by extraneous stimuli that have not been inhibited by larger goals or intentions.
• Negative signs, on the other hand, represent a defect in willed intention initiating behaviour. Much like the clinically depressed, schizophrenics with negative signs do not act. The critical distinction, as Frith puts it, is that depressives "do not want to act, while the schizophrenic patient cannot want to act."

• If there is a deficit of willed action, one consequence is that there will be no initiation of activity. This would lead to social withdrawal, poverty of action, and poverty of thought content
• A second consequence of a deficit in willed action would be that responding to irrelevant stimuli would not be edited out. This would lead to inappropriate action such as inappropriate affect, affective lability, and so on.
• Third, a failure of willed action would lead to failures in termination of otherwise appropriate responding (perseveration).

Defects in Self-Monitoring.

• One process thought important to self-monitoring is called "corollary discharge" or "reafference copy." Our intentions lead to a motor response, but there is also neural transmission that tells relevant parts of the brain of our intentions. This feed-forward mechanism allows us to distinguish between events due to our own actions, and events in the outside world.
• The impetus for positive signs is internally generated, but the corollary discharge has been lost. Internal experience needs to be tagged, in order to distinguish it from external experience. So an internally generated experience that has lost its tag (corollary discharge) will seem alien, and we would have the illusion that it is a perceptual experience external to thinking or imagining.

Defects in monitoring the intentions of others.

• The idea is that schizophrenics have difficulty in the social task of inferring the intentions of others and of perspective taking. One explanation for paranoid schizophrenia is that the person simply has a tremendous amount of difficulty inferring intentions from the behaviour of others. Paranoids adopt an interpretational stance where they infer hostility from otherwise innocuous behaviour.
• Note, however, that problems with monitoring the intentions of others are not only found in paranoid schizophrenia. For example, ideas of reference, where the person assumes others are talking about him or her, or the television is broadcasting specific messages specifically for him or her are examples of this kind of problem.
• Disorganized speech can also be thought of as due to a self-monitoring failure, where the perspective of the listener is no longer taken into account.

Metarepresentation

• Metarepresentation means the ability to mentalize or think about thinking.
• This would include such processes as knowing about your own intentions, knowing about goals, and the ability to represent (think about) the internal state of someone else.
• In this way, all schizophrenic deficits are in some way a part of this higher order deficit.
• Metarepresentation is important for keeping track of your own goals and intentions, as well as those of others.