Contrast Effects: Shifts in Work Load

The observation of contrast effects (CE) in response
to differential relnforcenent has subsequently elicited a
diversity of experimental results and theoretical interpretations. Adaptation Level (AL ) concepts have provided
a mechanism for integrating such data within a psychophysical
frame-of-reference approach. The application of
this approach to the somewhat neglected area of response-produced
stimuli associated with effort, suggests that
proprioceptive stimuli may be effectively evaluated in a
simllar manner. Following shifts in the amount of effort
required to produce a constant reward magnitude, performance
measures demonstrated positive and negative contrast
effects (PCE; NCE) in relation to an appropriate control
performance. Data analysis suggested that the combined
effects of greater effort and shift conditions tended to
increase resistance to extinction. The findings are not
consistent Kith traditional (e. g., Hull, Spence) concepts
with regard to CE and the influence of effort on performance. It is suggested that such effects are more consistent with a contextual, or frame-of- reference, viewpoint.