Instruction effects and relation between extraversion and the spiral aftereffect

The relation between extraversion (EPI) and length of aftereffect was investigated when spiral aftereffect was measured on the same Ss under three instructions: (a) normal— S is told to report “When the aftereffect appears to stop” and after Ss had been informed of two phases in the decay of the aftereffect and told to (b) report the end of the first, faster, phase of decay, or (c) report when “they were absolutely sure that the second phase of decay had ended.” Near zero correlations were obtained between E and SAE under conditions (a) and (c) but E and SAE were negatively and significantly correlated under condition (b). It is suggested that failure to differentiate these instruction conditions could account for many of the previous contradictory findings on the relation between E and SAE duration.

Some normative data for the spiral aftereffect

67 college students were exposed to the spiral aftereffect (SAE) in varied combinations of stimulation time and direction of rotation to observe the frequency and duration of SAE for a normal population. It was noted: (a) Men report slightly more AEs than women. (b) More men than women always report an AE. (c) AE reports increase with longer inspection times. (d) Expansion AEs occur more often and last longer than contraction AEs. (e) Reversal stimulation yields fewer AE reports of shorter duration and has a greater effect on contraction AE than expansion AE, and (f) the relation between stimulation time and AE duration is not linear.