Abstract
Purpose::
To investigate whether the differences reported between introverts and extraverts in internal arousal and sensitivity to external stimuli were reflected in performance on the antisaccade task.
Methods::
A web-based version of Eysenck's EPQRS personality questionnaire was advertised and individuals scoring at the bottom and top of the scale and, subsequently, around the median were invited to take part. Those responding and meeting selection criteria were between 18 and 30, with 19 introverts, 25 extraverts and 23 "ambiverts" in the middle. They were tested on an antisaccade task (40 trials, targets at +/-5 and 10 deg). Eye movements were recorded with an infrared limbus tracker, digitised and analysed off-line. Error rates and latencies for both correct antisaccades and reflexive errors were compared between introverts and extraverts with t-tests; after adding values for ambiverts, a linear regression was carried out for error rate against extraversion score.
Results::
Extraverts made significantly more errors than introverts (10.36±6.6 vs. 6.421±4.41,t=2.235, p=0.0308). When ambiverts were added, the regression was significant (r2 = 0.0691, p = 0.032). Latencies did not differ between extraverts and introverts for correct antisaccades (0.286±0.018 vs. 0.2783 ± 0.01128).
Conclusions::
Our initial hypothesis, that the higher dependence of extraverts on external arousal would make it harder for them to suppress unwanted reflexive responses on the antisaccade task, was supported by the results. The absence of a difference in latency suggests that introverts did not make fewer errors simply be taking more time to carefully respond. Although recent imaging studies have found differences in brain activity between introverts and extraverts in carrying out a range of tasks, this is one of the few to show a performance difference. Extraversion may thus contribute a small but significant amount to variability seen in performance on this task, even in normal subjects.
Keywords: eye movements: saccades and pursuits • eye movements: conjugate • eye movements