Behavioural Variability and Sequence Learning Across Species: Hens, Possums, and Humans

Understanding how reinforced variability contributes to both animal and human learning is critical in contexts where behavioural variability is an essential attribute of the operant behaviour. Reinforced variability may prove to have some benefits not evident in traditional operant learning procedures, such as its ability to promote generalisation of the operant to new contexts (e.g., Kong, McEwan, Bizo, & Foster, 2019; Neuringer, Deiss & Olson, 2000), and adding to its resistance to extinction (Neuringer, Kornell & Olufs, 2001). While inconsistencies exist between results from animal and human studies, there is evidence to suggest that reinforced variability may prove to be beneficial as a learning tool for humans in areas such as creativity, skill acquisition, as well as in the development of more productive treatments for some areas of psychopathology (e.g., Hopkinson & Neuringer, 2003; Saldana & Neuringer, 1998). Both empirical and applied studies provide evidence for the importance of understanding reinforced variability as a deeper understanding of it may allow for further development of learning technologies for promoting and maintaining variable responding in contexts where that is a desired characteristic of behaviour. The series of experiments in this dissertation addressed methodological concerns that have been raised by others in previous studies on reinforced variability (e.g., Doolan & Bizo, 2013; Maes & van der Goot, 2006; Neuringer et al., 2000) in an attempt to identify those factors that may moderate the learning of a response sequence by humans and non-humans. These experiments have explored the role reinforced variability plays in the learning of target sequences by modifying the methodology of previous studies to more closely replicate the work of Neuringer et al. (2000) with three species (humans, hens & possums). For the human component of the dissertation, three experiments explored the role of reinforced variability in sequence learning. In Experiment 1, in separate conditions, participants either had a visual record of the sequence components, as they were selected and displayed on a computer screen or had no record of the sequence components, and in both conditions, participants were given feedback after the last component was entered. Participants earned points for producing the target sequence. In conditions where variability in some aspect of the operant was a contingent requirement for reinforcement, participants experienced a secondary contingency for which they could earn points for producing sequences that met a variability criterion. In Experiment 2, the sequence length was manipulated and was either nine- or 12-digits long. Experiment 3 was a partial replication of Experiments 1 and 2 but with minimal task instruction. For the shorter six-digit sequences used in the No-Record condition of Experiment 1, direct reinforcement of the target sequence promoted higher production of the target sequence compared to the reinforcement of sequence variability. For a nine-digit sequence, the added requirement of variability promoted better learning of the target sequence than did direct reinforcement of the target sequence alone. There was no difference between the groups for the 12-digit sequence. The results of Experiment 1 replicate previous findings with humans on this procedure, while the results from Experiment 2, where a nine-digit sequence was required, were more consistent with reports from studies using a similar procedure with animals rather than human participants. The removal of detailed instructions in Experiment 3 appeared to increase the difference in the pattern of responding for the two groups for the six-digit sequence condition, suggesting that the difference between animal and human studies on behavioural variability is both a function of instruction and display of the just-completed sequence. For the non-human component of the dissertation, five separate experiments explored factors that affect behavioural variability and learning by hens (Experiments 4, 6, 7, & 8) and possums (Experiment 5). Experiments 4 and 5 were partial replications of Neuringer et al. (2000) and explored the role of reinforced variability in sequence learning in non-human animals. For Experiment 4, eighteen Shaver Starcross hens (Gallus gallus domesticus) served as subjects. The experiments consisted of the same five experimental phases, as described by Neuringer et al. (2000). The target sequences consisted of Left (L) and Right (R) key pecks and were the same for all hens and experimental groups across each phase (RLL, LLR, RRLR, LR, & RLLRL). The hens in the Control group could earn reinforcement for emitting the target sequence only. The hens in the Variable group could earn reinforcement for emitting the target sequence and producing a sequence that met the variability criteria. The hens in the Any group could also earn reinforcement for emitting the target sequence and on a variable interval (VI) 60-s schedule for any sequence they entered after the time interval had passed. Six Brushtail possums (Trichosurus vulpecula) served as the subjects for Experiment 5. The general procedure and first three phases of the experiment were the same as described above for Experiment 4, and the remaining phases were replaced with the remaining possible three-component sequences, RRL, LRL, RRR, LLL, RLR, LLR. Variability criteria for secondary reinforcement only facilitated more production of the target sequence compared to when there was secondary reinforcement for any sequence that was produced for the first phase of Experiment 4. There was no difference in target sequence production between the possums’ that only received direct reinforcement of the target sequence and those possums’ that were exposed to the secondary variability schedule in any of the five phases. In Phases 1-5 of Experiment 5, the pattern of responding was consistent with those reported by Neuringer et al. (2000) with their rats that were exposed to the secondary variability schedule producing more target sequences than the other experimental groups, however, the difference between groups was not significant. For the remaining phases, the Control group (i.e., direct reinforcement of the target sequence) produced the target sequence more frequently than the other experimental groups. However, the difference was not significant. In studies with humans, it has been suggested that responding may not be under the control of the reinforcement contingencies and that rules may influence responding such that behaviour must be considered rule-governed rather than contingency shaped, however, the comparable response patterns across species within this series of experiments suggest that there may be other individual differences that impact on the influence reinforced variability has on learning of a target sequence that had not yet been considered in previous research. A final series of experiments with hens explored the role that reinforced behavioural variability may play in the learning of a different non-sequence target behaviour by hens. Eighteen Shaver Starcross hens served as subjects in Experiments 6 - 8 and were required to make two screen pecks within a set target distance (distance bin) on a touchscreen to earn reinforcement. Experiment 6 was used as a baseline phase to ensure that the varying distance requirements were physically possible for the hens to complete. In Experiment 7, reinforcement was available for producing two consecutive pecks within the target distance bin, hens in the variability group would also earn reinforcement if their two consecutive pecks met a variability criterion. The hens could be exposed to both experimental conditions throughout the experiment as they were randomly allocated at the start of each phase. Experiment 8 compared six naive hens to six experienced hens from Experiment 7, to assess the role that previous exposure to the variability contingency may have on learning the target behaviour The original article by Neuringer et al. (2000) has been cited numerous times as a potential ‘game-changer' in both experimental and applied psychology, however, the findings of this series of experiments suggest that the benefits of reinforced variability in promoting the acquisition of a novel behaviour that Neuringer et al. reported with rats do not readily generalise across species or behavioural tasks. This calls into question the utility and potential benefits that might result from the application of these general principles in applied settings. It also highlights the limiting factors such as the nature of the operant, the difficulty of the task, and the instructions given to participants are important moderators of the impact of reinforcing behavioural variability on learning