The psychobiological correlates of schizotypy in a student sample
Growing evidence suggests psychotic symptoms such as auditory hallucinations may be
normally distributed and occur in non-clinical as well as clinical individuals. Schizotypy
is a measure of proneness to psychotic-like experiences. The aim of the study was to
identify individuals prone to psychotic-like experiences (High schizotypes) and
determine whether they differ from other individuals on psychological, behavioural and
cognitive measures. Additionally the biological correlates of hallucinatory-like
experiences were also investigated in high schizotypes.
Participants who scored highly, around the mean and low on positive schizotypy (as
defined by the Unusual Experiences subscale from the O-LIFE and the LSHS)
completed a number of psychological measures, the Neurological Evaluation Scale and
a signal detection task. Participants who produced a large number of False Alarms in the
signal detection task were asked to complete the task in a functional magnetic resonance
imaging (tMRI) scanner.
Using principal components analysis the O-LIFE items were explained by two
components: Cognitive Perceptual; and, Emotional and Social Functioning.
Multidimensional scaling revealed the LSHS could be explained using three
dimensions: Mental Imagery, Hallucinatory Experiences and their Explanations;
Auditory Imagery; and, Cognitive Misattributions. High schizotypes differed from at
least one of the other groups in reporting lifetime psychological symptoms, dissociative
experiences, suggestibility, metacognitive beliefs and general health. The High
schizo types displayed more neurological soft signs than the rest of the sample. In the
signal detection task the High group were less sensitive than the other participants,
although this did not reach significance. Both the High and Low groups demonstrated a
more liberal decision making style compared to the Mean group. However, only the
High group produced more False Alarms. The High group had the slowest reaction time
on the first repetition of the task but became faster across the three trials. fMRI results
for the High group participants revealed that False Alarms activated similar brain
regions to those associated with auditory hallucinations in patients with schizophrenia.
The O-LIFE and LSHS were successfully used to identify participants who scored
highly on schizotypy. Further research is needed to determine the nature of those who
score low on measures of schizotypy. Replication of the imaging study using a larger
sample of participants is required to confirm the exploratory findings reported here.