Evidence of contingency awareness in people with profound multiple impairments: response duration versus response rate indicators.

Evidence of contingency awareness in people with profound multiple impairments is often elusive due to numerous variables that impede learning and contribute to performance variability. Recent research has shown that measuring duration of responding rather than rate has promise for more accurate inferences. Duration measures of adaptive-switch use were obtained with 50 participants during empirical tests for contingency awareness. Nearly 80% had test performance patterns indicative of cause-and-effect learning or contingency awareness. Rate data were obtained concurrent with duration measures for 33/50 participants. Although statistical analysis indicated an interaction of test condition and rate of responding, the performance pattern indicative of contingency awareness was observed in only about 50% of the sets of rate data. Further, rate-based indications of contingency awareness were not consistently confirmed by the duration data. The results strongly support inclusion of response duration measures in evaluation of adaptive-switch use and contingency awareness.