Blocking as a function of novelty of CS and predictability of UCS

Kamin (1969) reported that after rats had been trained with one CS predicting shock, they learned virtually nothing about a second CS added to the first to form a compound—provided that the shock remained unchanged. If, however, the shock was either increased or omitted at the same time that the new CS was added, it acquired significant excitatory or inhibitory strength. Both these results were confirmed in the present experiment. In addition, however, it was found that this excitatory or inhibitory conditioning to the added element could itself be blocked if the shock remained unchanged for the first four trials after the addition of the new element. This finding implies that blocking is not due to any limitation on attentional or associative capacity, but rather occurs when subjects learn that a particular stimulus is redundant, i.e. that it predicts no change in reinforcement.

Dentists' voice control: effects on children's disruptive and affective behavior

Voice control, a punishment technique based on loud commands, has been used widely in pediatric dentistry. This study examined whether (a) loudness is a necessary component of the technique, (b) voice control actually reduces children's disruptive behavior, and (c) after treatment, children's negative affect increases. Subjects were forty 3 1/2- to 7-year-olds who posed potential behavior problems and who were scheduled for cavity restoration. Children were assigned randomly to either loud- or normal-voice groups. Children who were assigned to either group but who were not disruptive formed a nonexperimental control group. Prior to and after treatment, children reported their feelings using the Self-Assessment Mannequin. Disruptive behavior was scored using the Behavior Profile Rating Scale. Results indicated that, following loud, but not normal voice commands, children reduced their disruptive behavior (p less than .004) and self-reported lower arousal (p less than .09) and greater pleasure (p less than .10). Theoretical and practical implications of these findings are discussed.