Influence of physiognomic stimulus properties on afterimage adaptation

Autonomy of visual afterimages as tested by changing projection surface

If immature visual afterimages (AIs) are characterized by their lack of isolation from outside reality, they ought to be more sensitive to change in the projection surface than mature AIs. This proposition was tested in a group of 36 Ss confronted with two kinds of line patterns superimposed on the projection screen. AIs with immature stigmata (size-constancy, positive color, etc.) in an initial control series showed more deviations caused by these patterns than normally adult AIs. Even AIs with a loose or flexible structure in the control series tended to change; such AIs are not necessarily immature but rather reflect subjective contents overflowing the field of experience. In a second experiment, using 35 Ss, more complicated patterns were employed. All AIs here were more resistant to distortions.

Projected afterimages after manipulation of cognitive schemes in adults

Members of 14 pairs of 21-yr.-old men, matched with respect to general intelligence and educational background, were given different afterimage (AI) theories. One member was told that AIs are almost exclusively determined by subjective factors, the other that they are mainly controlled by the environment and, that phenomenologically they scarcely differ from real objects. In a subsequent AI experiment, with a projection distance 1.5 times the stimulation distance, the latter member reported images smaller than Emmert size, as well as positive hues, significantly more often than the former member, i.e., his AIs were more “childish” than those of the member encouraged to isolate his AI from the surrounding physical reality.

Afterimage change in children following reversal of experimenter's theoretical message

A previous finding by the present authors, that children's afterimages (AI) may be affected by the AI theory presented to them, was cross-validated in a sample of 29, aged 9 to 10 yr. The present study, where instructions were suddenly reversed in the middle of a series of 10 AI measurements, also showed that instruction effects were facilitated both by the child's ability to comprehend the instruction and the degree of correspondence between the “theoretical” message and the child's level of maturity.