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 distinguished using this procedure. Several reasons could

 account for this problem. As mentioned above, the reward

 situation is not as emotionally arousing as the shock

 condition. Since SCR is found to be highly correlated with

 arousal rating (Greenwald, Cook, and Lang, 1989), the lack

 of SCR in the reward condition may be related to the lack of

 arousal experienced by the subjects in this condition.

 Additionally, facial EMG which have been correlated with

 ratings of valence, does not appear to be a useful measure

 in this population.

 Third, since subjects were not asked to respond in any

way during the anticipatory period, it is unclear whether

subjects were accurately interpreting the emotional context

of the anticipation period on a trial by trial basis.

Although subjects demonstrated competence at distinguishing

the high and low pairs of tones from one another before the

onset of the experiment, some subjects may have difficulty

distinguishing certain tones or remembering the significance

of the tones during the experimental procedure. As a

consequence, the lack of SCR findings in the RHD group and

most of the subjects in the LHD group could possibly be

reflective of problems accurately interpreting the

significance of the anticipatory period.

 Lastly, attempts were made to map each subject's scans

onto Damasio's templates. However, this study was not

designed to be able to carefully determine the