• Orienting response;
  • GSR;
  • Habituation;
  • Base admittance level;
  • 2-stage hypothesis


Forty-eight Ss received 10 repetitive 1-sec light presentations at either 5 or 25 foot candles (ft c), followed by a switch on Trial 11. After approximately 2 months the experiment was repeated. Of 34 Ss who correctly described the stimulus change on initial testing, only 18 gave a (GSR) OR. On retest, most Ss retained their characteristic response, but previously responsive 25 [RIGHTWARDS ARROW] 5 ft c. Ss became non-responsive on Trial 11. There were no differences between OR-responders and non-responders to Trial 1 flash though responders subsequently took longer to habituate and made more ORs overall. There was no difference in base admittance (BAL) increase following initial onset of stimulation, but OR-responders subsequently showed a continuing BAL rise while nonresponders returned to resting levels. The OR is not an automatic accompaniment to perceptible stimulus novelty. A 2-stage process was hypothesized in triggering an OR, stressing the role of cognitive-motivational variables.