Schizotypy and Conditional Reasoning

Abstract

This study investigated the role of reasoning biases in delusion formation and maintenance. Reasoning judgments have been shown to be influenced by prior knowledge, beliefs, and experience--that is, information stored in semantic memory. It was hypothesized that high schizotypes would exhibit a "jump to conclusions" style of reasoning as a result of not using implicit information concerned with cause-effect relationships. Research into human reasoning has traditionally adopted logic as a normative framework to assess human reasoning. Conditional inference tasks are direct tests of logical performance, and we employed an established design that depends upon the reasoner's ability to access and use implicit information. In an effort to negate some of the difficulties of research with schizophrenia patients, schizotypy measures were employed in a normal population. The results confirmed that high scorers on one dimension of schizotypy (Impulsive Nonconformity) failed to take account of the number of counterexamples that characterized the cause-effect conditional statement. These observations supported previous research demonstrating a jump to conclusions style of reasoning that it has been suggested plays a role in the formation and maintenance of delusions. Furthermore, these findings suggest a possible link between semantic memory and reasoning biases.

Jumping to conclusions: A network model predicts schizophrenic patients' performance on a probabilistic reasoning task

“…Significant effects were found only on the data-gathering task and the probability-judgment task, leading Linney et al (1998) to argue that delusion ideation is caused only by data-gathering abnormalities. The evidence from both studies involving normal populations (Sellen et al, 2005;Linney et al, 1998) demonstrate that different reasoning tasks-using different methodologies and measures of delusion proneness-result in a specific data-gathering bias. This is consistent with a jump-toconclusions reasoning bias, not a quick-to-respond bias.…”

“…Evidence that delusional states are associated with a reasoning bias rather than a "speak-too-soon" bias may be found in studies of a normal population (see, e.g., Linney, Peters, & Ayton, 1998;Sellen, Oaksford, & Gray, 2005). Sellen et al differentiated between participants using the impulsive-nonconformity factor of the Oxford-Liverpool inventory of feelings and experiences (Mason, Claridge, & Jackson, 1995).…”

“…Delusional states were observed in both affective and schizophrenic psychoses. The impulsive-nonconformity factor is argued to measure an underlying common disposition, under the assumption that affective and schizophrenic psychoses coexist along a continuum (Sellen et al, 2005). Thus, high scores on the impulsive-nonconformity factor may reflect a general psychosis proneness, or a proneness to delusions.…”

Individual differences are more than a gene × environment interaction: The role of learning.

“…For example, De Houwer, Vandorpe and Beckers (2005) argued that blocking in human learning can result from participants drawing higher level inferences of the form "cues A and B together cause the outcome to occur with the same probability as does cue A alone; this implies that cue B is Individual Differences 33 not a cause of the outcome." From this approach, individual difference in blocking may reflect individual difference in inferential reasoning rather than attention (e.g., Garety, Hemsley & Wessely, 1991;Mitchell et al, 2009;Sellen, Oaksford & Gray, 2005), which itself may involve a complex form of associative generalization.Schizotypy-related differences in learning, have also been studied using complex configural discriminations (e.g., Haddon, George, Grayson, McGowan, Honey and Killcross, 2011). Individuals with high levels of introverted anhedonia are impaired solving a biconditional discrimination, suggesting an inability to treat the co-occurrence of stimuli as a unique configuration.…”

Probabilities, causation, and logic programming in conditional reasoning: reply to Stenning and Van Lambalgen (2016)

“…The experiments they cite would be more compelling if LP were the only theory that predicts apparently dysfunctional exception handling and these were the only experiments demonstrating this phenomenon. However, we have shown dysfunctional exception handling in high schyzotypes (Sellen, Oaksford, & Gray, 2005). High schizotypes showed no effect of many disablers in a replication of Cummins (1995) with high and low schizotypy groups.…”