Neuroticism, recall bias and attention bias for valenced probes: a twin study

BACKGROUND

Prior research on the nature of the vulnerability of neuroticism to psychopathology suggests biases in information processing towards emotional rather than neutral information. It is unclear to what extent this relationship can be explained by genetic or environmental factors.

METHOD

The genetic relationship between a neuroticism composite score and free recall of pleasant and unpleasant words and the reaction time on negative probes (dot-probe task) was investigated in 125 female twin pairs. Interaction effects were modelled to test whether the correlation between neuroticism and cognitive measures depended on the level of the neuroticism score.

RESULTS

The only significant correlation was between neuroticism and the proportion of recalled unpleasant words (heritability is 30%), and was only detectable at the higher end of the neuroticism distribution. This interaction effect seems to be due to environmental effects that make people in the same family more similar (e.g. parental discipline style), rather than genetic factors. An interesting sub-finding was that faster reaction times for left versus right visual field probes in the dot-probe task suggest that cognitive processing in the right hemisphere is more sensitive to subliminal (biologically relevant) cues and that this characteristic is under substantial genetic control (49%). Individual differences in reaction times on right visual field probes were due to environmental effects only.

CONCLUSIONS

There is no evidence that the predisposition of individuals to focus on negative (emotional) stimuli is a possible underlying genetic mechanism of neuroticism.

Free recall of pleasant words from recency positions is especially sensitive to acute administration of cortisol

In a recent study we investigated the acute effects of cortisol administration in healthy male volunteers on free recall of pleasant, unpleasant, and neutral nouns using a between-subjects double-blind placebo-controlled design. The volunteers were administered 10 mg of hydrocortisone or placebo between 9:00 and 10:30. Two hours after administration of cortisol a decline in recall of neutral and pleasant words was found, while recall of unpleasant words did not change. These results are consistent with a possible inhibitory influence of cortisol on a prefrontal dopaminergic mechanism involved in approach and positivity bias. In this paper we first explain why this interpretation would predict recall of pleasant words from recency positions to be especially sensitive to cortisol administration. Comparing primacy and recency recall of pleasant and unpleasant words, there proved to be a selective decline in recall of pleasant recency words. These results did not appear to stem from differences in recall strategies between our groups of volunteers.