Hypnotic susceptibility, interference, and alternation frequency to the Necker cube illusion.

Two experiments (N = 60) were conducted to determine the effects of hypnotic susceptibility and interference on frequency of Necker cube apparent reversals (ARs). Interference was induced in Experiment 1 by having subjects respond to orally administered double-digit arithmetic (addition) problems while observing the Necker cube. In Experiment 2, counting backward by 3s served as interference. In both experiments, interference reduced ARs. Hypnotic susceptibility level also influenced ARs, with those scoring high on this attribute reporting more ARs than those scoring low. Attentional factors may have played a major role in producing the reported results.