COGPID: Cognitive Processes in Decisionmaking

Psychosis is a disorder, which manifests itself in social interactions. This is
most evident in the core symptoms of psychosis, especially paranoid delusions
that are characterised by a fundamental lack of trust. The neurocognitive
approach, which represents the largest area of cognition research in psychosis,
has not adequately incorporated the social quality of psychotic symptoms, and,
as a consequence, has had limited power in explaining the mechanisms of symptom
formation. While there is renewed interest in social cognition and its
potential as a paradigm to elucidate symptom formation, until recently, this
has failed to consider the interactive character of social processes, and there
were few experimental paradigms able to address this. This has changed with the
development of *neuro-economics*, or the adaptation of behavioural economics
and game-theoretical approaches. These paradigms have promise in filling this
explanatory gap, but have as yet not been applied systematically to the study
of psychosis.

The heterogeneity of psychotic disorders, such as schizophrenia, has led
researchers to increasingly focus on a single characteristic symptom. While
most previous work has focussed on auditory hallucinations, this study will
focus on paranoid delusions, the rationale being the predominantly social
nature of these phenomena as well as their clinical importance, and their
association with significant disability and distress. There is now ample
evidence that the mechanisms that lead to symptoms of psychosis also operate in
individuals at lower levels of a hypothesised psychosis continuum, such as
individuals with non-clinical psychotic experiences and first-degree relatives
of patients with psychosis. Therefore, paranoid delusions will be investigated
at the level of the clinical disorder, but also at a subclinical level in
healthy individuals, where they may manifest as suspiciousness, feelings of ill
will or resentment and belief in external control. This is important from a
conceptual standpoint, because it will help to elucidate mechanisms of
transitions over the psychosis continuum, but also methodologically, as
investigation of cognitive processes in healthy individuals overcomes the
confounding effects of antipsychotic medication which is used by almost all
patients at some point during their illness.

The aim of the project is to apply neuro-economics in order to elucidate
mechanisms underlying disturbed social cognition in paranoid delusions at the
level of the cognitive mechanisms. This will be done in patients with lifetime
presence of non-affective psychosis, the first-degree relatives of these
patients, individuals from the general population with subclinical paranoia,
and control subjects without a personal or family history of psychosis. By
including four groups at different positions at the paranoia continuum, the
relative contributions of these mechanisms in driving transitions over the
continuum can be investigated.

The first part of the study uses a quasi-experimental between subject design.
Participants will play a trust game. In a typical trust game person A is given
a certain amount of money. A has to decide whether to cooperate (i.e., to share
money) with a second person B or to defect (i.e., to keep money). Shared money
will be tripled and in a second step B decides whether to reciprocate A*s trust
(i.e., repay part of the money) or to defect (i.e., keep all the money).
Mutually beneficial outcomes are more likely if both players cooperate,
however, the best payoff for B given through defection. Therefore, sharing
money requires the investors trust. Whether aberrant sensitivity to the
motivational value of social interactions (or social reward) may be one of the
mechanisms underlying the basic loss of trust in paranoia will be assessed by
comparing trust (tendency to invest) and reciprocity (tendency to share money
as a function of rounds in the trust game ) across the study groups. The
effects of context (information on previous behavior of the partner) and
feedback (information about the reciprocity of the partner) on these factors
will be compared between the four experimental groups (independent variable).

Based on profound experience in cognitive research with psychotic patients that
previously has been conducted at the department the current projects are
regarded as involving minimal risk.