Evidence of contingency awareness in people with profound multiple impairments: response duration versus response rate indicators.
Time how long the switch is held, not how often it is pressed, to see if learners with profound impairments notice their control.
01Research in Context
What this study did
Rutherford et al. (2003) worked with adults who have profound multiple impairments. All used a single adaptive switch as their only response.
The team compared two ways to score the switch press: how many times it was hit (rate) and how long it was held (duration). They wanted to see which metric better showed the person knew their press produced a reward.
What they found
Duration won. Eighty percent of participants showed clear contingency awareness when the team looked at how long they held the switch. Only half looked aware when the team counted presses per minute.
In other words, learners held the switch longer when music or vibration followed, but they did not always press more often.
How this fits with other research
Schlundt et al. (1999) saw the same duration edge earlier. They reran ambiguous preference tests and got clearer reinforcer ranks by timing how long items were touched, foreshadowing the 2003 finding.
Kodak et al. (2009) echo the warning. They compared duration-based and selection-based preference assessments and also found the two methods disagreed for some learners, backing the idea that metric choice changes what you detect.
Kangas et al. (2011) extends the same insight. Using the same profound-impairment group and single-switch response, they showed you can also build a full preference hierarchy from minimal switch holds, complementing the 2003 focus on awareness detection.
Why it matters
If you support learners with limited movement, start timing switch holds instead of just tallying presses. A free-operant duration record is easy: hold a stopwatch whenever the client activates the toy. You will spot contingency awareness faster and avoid false negatives that can stall programming.
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02At a glance
03Original abstract
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.
Research in developmental disabilities, 2003 · doi:10.1016/s0891-4222(03)00040-4