Thursday, August 13, 2015 | 12:00 p.m.
Neville Scarfe Building, Room 2415
Title: The effect of schedules of reinforcement on the rate and force of the response during extinction
Supervisor: Dr. Joe Lucyshyn
Committee Member: Dr. Sterett Mercer
External Examiner: Dr. Griffin Rooker (Research Scientist, Kennedy Krieger Institute)
Approximately 30 to 40% of individuals diagnosed with autism display aggressive, SIB, or disruptive behaviour (i.e., problem behaviour). Although force is a defining aspect of problem behaviour, it has been largely overlooked in behavioural research. With the purpose of examining the influence of schedules of reinforcement on the force and rate of the response during extinction, I conducted two experiments in three individuals diagnosed with autism. Using a reversal design, one participant was exposed to VR5 followed by EXT (Experiment 1); and two participants were exposed to a sequence of VR5-CRF-EXT (Experiment 2). Findings of Experiment 1 in Participant 2 showed an increased level of force and variability during VR5 and extinction. The two participants of Experiment 2 (P-3 and P-4) demonstrated a similar pattern of force during VR5 with low and stable rates of response during CRF. Participant 3 showed increased force and force variability during CRF. Participant 4 exhibited a temporary increase of force during extinction that could be interpreted as extinction burst in force. An analysis of the distribution of force during the first and last day of extinction phases showed the presence of forceful responses during the first and last day of extinction. In summary, results suggested that: (a) force increases and becomes variable during extinction; (b) variable ratio and CRF schedules influence the level of force and force variability; (c) continuous reinforcement may have merit to reduce rate but not necessarily to reduce force of response; and (d) the covariation of force and rate is not always direct and should not be predicted from rate alone. I identified some potential limitations caused by the measurement device, the participants and the setting. Further research is needed to increase the generality of these results.