UCS-INFLATION AND ACQUIRED FEAR RESPONSES IN HUMAN CONDITIONING

Four experiments concerning UCS-inflation in humans were conducted emp loying a differential conditioning paradigm. In Experiment 1 (n = 30) one neutral slide (CS+) was paired with a mild electric shock (UCS) an d another neutral slide (CS-) was never paired with a shock. An inflat ion phase followed, during which unsignalled UCSs gradually increased in strength for the inflation group, while they were kept constant for the control group. During the post-inflation trials, only the inflati on group showed relatively large skin conductance responses (SCRs) on CS+ trials and prolonged differential UCS expectancies. Experiment 2 ( n = 20) was similar to the first experiment, with the exception that ( i) the UCS was inflated in only one trial, (ii) slides depicting angry faces were used as CSs and (iii) subjective evaluations of the CSs we re measured in addition to the SCRs. Neither at the physiological nor at the subjective level, conditioning effects emerged in the inflation group. In Experiment 3 (n = 42) and 4 (n = 33), erotic slides were us ed as CSs and a mild tone served as UCS. During the inflation stage, o nly the inflation group was told that the tone indicated, in fact, ''b lushing''. Experiment 4 sought to increase the aversiveness of the ''b lush'' manipulation by having two observers seated inside the experime ntal room. Though the ''blush'' manipulation appeared to successfully inflate the UCS, neither study revealed strong data confirming the ide a that human conditioned responding is susceptible to UCS-inflation. T hus, UCS-inflation in humans is, at best, a fragile phenomenon.