Perceptual Categorization: Connectionist Modelling and Decision Rules

Although it is currently popular to model human associative learning using connectionist networks, the mechanism by which their output activations are converted to probabilities of response has received relatively little attention. Several possible models of this decision process are considered here, including a simple ratio rule, a simple difference rule, their exponential versions, and a winner-take-all network. Two categorization experiments that attempt to dissociate these models are reported. Analogues of the experiments were presented to a single-layer, feed-forward, delta-rule network. Only the exponential ratio rule and the winner-take-all architecture, acting on the networks' output activations that corresponded to responses available on test, were capable of fully predicting the mean response results. In addition, unlike the exponential ratio rule, the winner-take-all model has the potential to predict latencies. Further studies will be required to determine whether latencies produced under more stringent conditions conform to the model's predictions.     

A comparison of isolated and synthesized contingencies in functional analyses

Recently, researchers have compared the utility of isolated versus synthesized contingencies in functional analysis (FA) methodology (e.g., Fisher et al., 2016; Slaton et al., 2017). A limitation of these studies is that there were other differences across FA methodologies (e.g., design, contingency) that did not allow for isolation of the influence of isolated versus synthesized contingencies. Therefore, the current study compared outcomes of FAs that involved isolated versus synthesized contingencies for problem behavior of 5 children while controlling for these other differences across FAs (Experiment 1). Next, the current study compared the effects of interventions based on the functions identified in the isolated and synthesized contingencies for each participant (Experiment 2). Results indicated isolated contingency FAs produced differentiated responding for 1 or both functions for all 5 participants, and there were little to no differences between treatments informed by isolated and synthesized contingency FAs.