STIMULUS EFFECTS ON LOCAL PREFERENCE: STIMULUS—RESPONSE CONTINGENCIES,STIMULUS—FOOD PAIRING,AND STIMULUS—FOOD CORRELATION

Four pigeons were trained in a procedure in which concurrent‐schedule food ratios changed unpredictably across seven unsignaled components after 10 food deliveries. Additional green‐key stimulus presentations also occurred on the two alternatives, sometimes in the same ratio as the component food ratio, and sometimes in the inverse ratio. In eight experimental conditions, we varied the contingencies surrounding these additional stimuli: In two conditions, stimulus onset and offset were noncontingent; in another two, stimulus onset was noncontingent, and offset was response contingent. In four conditions, both stimulus onset and offset were contingent, and in two of these conditions the stimulus was simultaneously paired with food delivery. Sensitivity to component food ratios was significantly higher when stimulus onset was response contingent compared to when it was noncontingent. Choice changes following food delivery were similar in all eight conditions. Choice changes following stimuli were smaller than those following food, and directionally were completely determined by the food‐ratio:stimulus‐ratio correlation, not by the stimulus contingency nor by whether the stimulus was paired with food or not. These results support the idea that conditional reinforcers may best be viewed as signals for next‐food location rather than as stimuli that have acquired hedonic value, at least when the signals are differential with respect to future conditions.     

Retrospective revaluation effects following serial compound training and target extinction

Using a conditioned suppression task, two experiments examined retrospective revaluation effects after serial compound training in a release from overshadowing design. In Experiment 1, serial X → A+ training produced suppression to target A, which was enhanced when preceded by feature X, whereas X by itself elicited no suppression. Subsequent A− presentations extinguished responding to A, but had no effect on either responding to X → A or X alone. However, the addition of A− trials did enhance the ability of feature X to elicit suppression to a novel target, B, suggesting retrospective revaluation of X’s properties. Experiment 2 showed that the enhanced transfer effect, observed in Experiment 1, was independent of the training history of the target (B− or Y → B+/B−). Together, these results suggest that feature X did not retrospectively acquire excitatory strength or occasion setting power, but rather a generalized ability to increase responding to any other cue.     

A decision model for steady-state choice in concurrent chains

Grace and McLean (2006) proposed a decision model for acquisition of choice in concurrent chains which assumes that after reinforcement in a terminal link, subjects make a discrimination whether the preceding reinforcer delay was short or long relative to a criterion. Their model was subsequently extended by Christensen and Grace (2008, 2009a, 2009b) to include effects of initial- and terminal-link duration on choice. We show that an expression for steady-state responding can be derived from the decision model, which enables a model for choice that provides an account of archival data that is equal or superior to the contextual choice model (Grace, 1994) and hyperbolic value-added model (Mazur, 2001) in terms of goodness of fit, parsimony, and parameter invariance. The success of the steady-state decision model validates the strategy of understanding acquisition phenomena as a bridge toward explaining choice at the molar level.     

Dual effects on choice of conditioned reinforcement frequency and conditioned reinforcement value

Pigeons were presented with a concurrent‐chains schedule in which the total time to primary reinforcement was equated for the two alternatives (VI 30 s VI 60 s vs. VI 60 s VI 30 s). In one set of conditions, the terminal links were signaled by the same stimulus, and in another set of conditions they were signaled by different stimuli. Choice was in favor of the shorter terminal link when the terminal links were differentially signaled but in favor of the shorter initial link (and longer terminal link) when the terminal links shared the same stimulus. Preference reversed regularly with reversals of the stimulus condition and was unrelated to the discrimination between the two terminal links during the nondifferential stimulus condition. The present results suggest that the relative value of the terminal‐link stimuli and the relative rate of conditioned reinforcer presentation are important influences on choice behavior, and that models of conditioned reinforcement need to include both factors.     

A low‐cost platform for eye‐tracking research: Using Pupil© in behavior analysis

Tracking eye movements is being increasingly recognized as a valuable source of information about stimulus control. So far, however, eye‐tracking research has suffered from accessibility issues, with expensive hardware and closed‐source software. In this article we review Pupil©, an eye‐tracking platform developed by Pupil Labs and that combines open‐source software with low‐cost hardware components. We offer concrete recommendations about Pupil use in stimulus‐control research and we show how the software can be extended to automatize the analysis of gaze data. Finally, we present the results of a study of visual discrimination and conditioned reinforcement conducted with Pupil, establishing the usefulness of this platform as a research tool in behavior analysis.     

Temporal context, preference, and resistance to change

According to behavioral momentum theory, preference and relative resistance to change in concurrent-chains schedules are correlated and reflect the relative conditioned value of discriminative stimuli. In the present study, we explore the generality of this relation by manipulating the temporal context within a concurrent-chains procedure through changes in the duration of the initial links. Consistent with previous findings, preference for a richer terminal link was less extreme with longer initial links across three experiments with pigeons. In Experiment 1, relative resistance to change and preference were related inversely when responding was disrupted with response-independent food presentations during initial links, replicating a previous finding with rats. However, more food was presented with longer initial links, confounding the disrupter and initial-link duration. In Experiment 2, presession feeding was used instead and eliminated the negative relation between relative resistance to change and preference, but relative resistance to change was not sensitive to relative terminal-link reinforcement rates. In Experiment 3, with more extreme relative terminal-link reinforcement rates, increasing initial-link duration similarly decreased preference and relative resistance to change for the richer terminal link. Thus, when conditions of disruption are equal and assessed under the appropriate reinforcement conditions, changes in temporal context impact relative resistance to change and preference similarly.     

A COMPARISON OF TWO PAIRING PROCEDURES TO ESTABLISH PRAISE AS A REINFORCER

Some individuals with intellectual disabilities do not respond to praise as a reinforcer, which may limit their ability to learn. We evaluated 2 procedures (stimulus pairing and response—stimulus pairing), both of which involved pairing previously neutral praise statements with preferred edible items, to determine their usefulness in establishing praise as a reinforcer. Results of Study 1 indicated that stimulus pairing was not effective in conditioning praise as a reinforcer for 3 of 4 subjects; results were inconclusive for the 4th subject. Results of Study 2 indicated that response—stimulus pairing was effective in conditioning praise as a reinforcer for 4 of 8 subjects. After conditioning, praise also increased the occurrence of additional target responses for these 4 subjects.     

OBSERVATIONAL EFFECTS ON THE PREFERENCES OF CHILDREN WITH AUTISM

Children with an autism spectrum disorder (ASD) may play with limited objects or toys, making it difficult for teachers to identify reinforcers to use in teaching new skills. The goal of this study was to alter children's preferences from highly preferred toys to toys that were originally less preferred using an observational pairing procedure. Child participants observed a preferred adult playing with toys that were initially less preferred by the child. This intervention resulted in a shift in preference toward the item manipulated by the adult. Maintenance of the changed preference was idiosyncratic across participants. Results suggest a procedure for expanding the range of items that students with ASD will select.