Are Creativity and Schizotypy Products of a Right Hemisphere Bias?

©2000 Sara Weinstein

University of Victoria

Background

Schizotypy is a continuous construct measurable in the normal population.  An individual who scores high on a measure of schizotypy is someone who is inclined to hold paranormal beliefs, have unusual subjective sensory and somatic experiences, and be less socially oriented.  Essentially, these are healthy individuals whose response patterns on various scales mimic the response patterns of schizophrenics.

Laterality is the degree to which the two hemispheres of the brain are functionally or anatomically different; this term can imply hemispheric ‘dominance’.

Previous research has established the following associations:

a)     creativity and schizotypy – positive correlation.

b)     creativity and laterality – higher creativity with relatively greater reliance on the right hemisphere.

c)      schizotypy and laterality – higher schizotypy with relatively greater reliance on the right hemisphere.

Theoretical View

It has been hypothesized that decreased left hemisphere dominance for language results in an over-reliance on the right hemisphere of the brain for semantic processing (the perception and interpretation of meaning in incoming sensory information).  

The subsequent increase in right hemisphere semantic activation is thought to be the causal mechanism underlying creative, schizotypal, and schizophrenic thought.

The implication of a common causal mechanism is that creativity, schizotypy, and schizophrenia are all manifestations of the same trait, being expressed to a different degree.

The authors’ previous study used signal detection theory and found that positive schizotypy and creativity were related to a biasing component of laterality rather than actual hemispheric ability, when laterality was measured with a lexical decision task. 

This implies that those individuals who score highly on creativity and schizotypy are placing more confidence in the right hemisphere processes, not just performing at a higher level with them.

Research Goals

Using the same measures that established these relationships previously, the author intended:

I.                     To replicate the three previously established pairwise relationships among creativity, schizotypy, and laterality.

II.                   To substantiate the claim that creativity and schizotypy are related to a biased response strategy, rather than hemispheric ability.

By inclusion of a second laterality measure, dichotic listening, the author intended:

III.                  To strengthen the laterality results identifying response strategy as the as the facet of laterality linked with creativity and schizotypy.

Sample

Participants were 60 University of Victoria undergraduate students receiving credit in Psychology 100, meeting the following criteria:

a)     No history of psychological/neurological disorder

b)     Normal or corrected-to-normal vision and hearing

c)      Good understanding of the English language

The sample was comprised of 21 men and 39 women, with a mean age of 19.8.

Analysis of the laterality tasks required exclusion of several participants, whose scores were too extreme for signal detection analysis (which is compromised by extreme values).  Lexical decision requirements dropped N to 46, and dichotic listening had N = 48.

Materials

Schizotypy

1.      Magical Ideation Scale: measure of paranormal belief.

2.      Perceptual Aberration Scale: measure of subjective somatic/sensory experiences.

3.      Social Anhedonia Scale: measure of social preferences.

Creativity

1.      Remote Associates Test: ability to produce conceptually distant associations.

2.      Thurstone Written Fluency Test: ability to produce words meeting specific criteria.

Laterality

1.      Lexical decision: measure of lateralized visual performance on a word recognition task.

2.      Dichotic listening: measure of lateralized auditory performance on a syllable recognition task.

Data Reduction

Perceptual Aberration and Magical Ideation (having a high positive correlation) were collapsed to form the schizotypy variable ‘Per-Mag’, as is customary in the literature.

The two parts of the Thurstone Written Fluency Test also had a significant positive correlation and were collapsed, forming the creativity variable ‘Written Fluency’.

Measures of detection ability (A¢) and response bias (B¢¢) were calculated for each visual field in the lexical decision task and each ear in the dichotic listening task, using signal detection theory.  Indices of relative hemispheric importance in each measure (A2 and B2) were then calculated as right minus left differences.

·        Higher A2 values indicate better right-sided (left hemisphere) detection ability.

·        Higher B2 indices indicate a response bias favouring the right hemisphere.

The Social Anhedonia and Remote Associates Test scores were retained as measured.

Results

Part 1: Replication of Pairwise Relationships

As seen in Table 1, bivariate correlation of the original six variables produced three significant correlations out of 15.  The Remote Associates Test correlated significantly with Written Fluency, r = .259, p = .023, indicating concordance between these two measures.

Schizotypy correlated with both creativity measures, with  r = .302, p = .009 for Per-Mag with Remote Associates Test, and r = .218, p = .047 for Per-Mag with Written Fluency, indicating co-occurrence of creative and schizotypal thought.

 Finally, Remote Associates and B2L were correlated, r = .275, p = .032, relating high creativity with biased response strategy favouring the right hemisphere. 

Part 2: Substantiation of Laterality Findings

The correlations were re-run with the dichotic listening measures in place of the lexical decision measures.  One of the subsequent eight correlations was significant, Social Anhedonia with A2D, r = .379, p = .004, as seen in Table 2.  This correlation indicates that high Social Anhedonia is related to lateralized detection ability of the left hemisphere, relative to the right.

Conclusion

The relationship observed between creativity and schizotypy demonstrates successful replication of previous results, lending further support to the idea of a common cognitive process underlying creative and schizotypal thought.

The creativity-laterality results are also as hypothesized, as the correlation between the Remote Associates Test and the B2L laterality measure indicate that creativity is related to a response strategy favouring the right hemisphere.

Attempts to substantiate the relationship between schizotypy and laterality received indirect support. Schizotypy is a multidimensional construct, and Social Anhedonia is considered to be opposite in nature to the Per-Mag construct (labelled as negative and positive facets, respectively).  The correlation between Social Anhedonia and A2D, indicating better detection ability with the left hemisphere, could accord with the theory under investigation as this facet of schizotypy is in opposition to that usually linked with the right hemisphere.

Although only partial replication was achieved, several more correlations approached significance in the hypothesized directions, indicating that the effects sought may be present, but too small to be statistically significant.  Meta-analysis of these results with previous results is planned to determine if this is the case.