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 followed by a discussion of the results with the stroke

 patients.

 Differential Responding in Normal Subjects

 Shock Condition

 Heart rate

 In the normal subjects, heart rate was expected to be

 greater during the shock compared to the no-shock condition.

 Additionally, a heart rate wave form, with an initial

 deceleration, followed by an acceleration, and then a second

 deceleration was expected during the shock condition. This

 wave form was expected to be attenuated during the no-shock

 control trials.

 Heart rate did not differentiate the shock from the

 control trials within the normal controls. There are

 several possible explanations for the lack of significance

 between the shock and control trials.

 First, heart rate tends to differ depending on the

 response-set of the subjects. For example, heart rate wave

 forms have been found to be much more pronounced when

 subjects are supposed to respond in some way at the end of

 the anticipation period (Lang, Ohman, Simons, 1978). In a

 recent study, when subjects were asked to react to a noxious

 noise which followed a 6 second warning cue, they had

 greater heart rate decelerations during the anticipation

 period than subjects who were not asked to respond in any

way (Patrick & Berthot, 1995). This study, however,