Resistance to change and relapse of observing

Four experiments examined relapse of extinguished observing behavior of pigeons using a two-component multiple schedule of observing-response procedures. In both components, unsignaled periods of variable-interval (VI) food reinforcement alternated with extinction and observing responses produced stimuli associated with the availability of the VI schedule (i.e., S+). The components differed in the rate of food arranged (Rich = VI 30 s; Lean = VI 120 s). In Experiment 1, following baseline training, extinction of observing involved removal of both food and S+ deliveries, and reinstatement was examined by presenting either response-independent food or S+ deliveries. In Experiment 2, extinction involved removal of only food deliveries while observing responses continued to produce S+. Reinstatement was examined by delivering food contingent upon the first two food-key responses occurring in the presence of the S+. Experiment 3 assessed ABA renewal of observing by extinguishing food-key and observing responses in the presence of one contextual stimulus (i.e., B) and then returning to the original training context (i.e., A) during continued extinction. Experiment 4 examined resurgence by introducing food reinforcement for an alternative response during extinction, and subsequently removing that alternative source of food. Across experiments, relative resistance to extinction and relapse of observing tended to be greater in the component previously associated with the higher rate of primary reinforcement. Relapse of observing or attending to stimuli associated with primary reinforcement appears to be impacted by frequency of primary reinforcement in a manner similar to responding maintained directly by primary reinforcement.     

Rapid acquisition of bias in signal detection: dynamics of effective reinforcement allocation

We investigated changes in bias (preference for one response alternative) in signal detection when relative reinforcer frequency for correct responses varied across sessions. In Experiment 1, 4 rats responded in a two-stimulus, two-response identification procedure employing temporal stimuli (short vs. long houselight presentations). Relative reinforcer frequency varied according to a 31-step pseudorandom binary sequence and stimulus duration difference varied over two values across conditions. In Experiment 2, 3 rats responded in a five-stimulus, two-response classification procedure employing temporal stimuli. Relative reinforcer frequency was varied according to a 36-step pseudorandom ternary sequence. Results of both experiments were analyzed according to a behavioral model of detection. The model was extended to incorporate the effects of current and previous session reinforcer frequency ratios on current-session performance. Similar to findings with concurrent schedules, effects on bias of relative reinforcer frequency were highest for the current session. However, carryover from reinforcer ratios of previous sessions was evident. Generally, the results indicate that bias can come under control of frequent changes in relative reinforcer frequency in both identification and classification procedures.     

Protecting Against Low‐Probability Disasters: The Role of Worry

We carry out a large monetary stakes insurance experiment with very small probabilities of losses and ambiguous as well as exact probabilities. Many individuals do not want to pay anything for insurance whether the probabilities are given exactly or are ambiguous. Many others, however, are willing to pay surprisingly large amounts. With ambiguity, the percentage of those paying nothing is smaller and the willingness to pay (WTP) of the other individuals larger than with exact probabilities. Comparing elasticities with ambiguity, we find that worry is much more important than subjective probability in determining WTP for insurance. Furthermore, when the ambiguous loss probability is increased by a factor of 1000, it has almost no effect on WTP. Copyright © 2011 John Wiley & Sons, Ltd.     

Disjunction Between Probability and Verdict in Juror Decision Making

Although the law assumes a close relation between the probability that a defendant committed the act in question and the ensuing verdict of the jurors, prior research has shown this assumption to be often violated. We present five experiments designed to show that factors that influence probability also influence verdict, but other factors are capable of directly producing changes in verdict without affecting probability. In Experiment 1, we replicated the Wells Effect; scenarios generating the same probability that the Blue Bus Company was to blame for the same accident, nevertheless, generated significantly different likelihoods of finding the defendant liable. In Experiment 2, we showed that equally diagnostic affirmative and negative evidence had differential effects on mock jurors' probability estimates and verdicts. In Experiment 3, we showed that a completely nondiagnostic witness, who either implicates the same bus company or a different bus company as did a diagnostic witness, significantly influenced mock jurors' verdicts. However, the nondiagnostic witness did not change the probability that the Blue Bus Company was responsible for the accident. In Experiment 4, we demonstrated that base rate and witness reliability information resulted in very similar probability estimates but radically different verdicts. In Experiment 5, we showed that a change in the diagnosticity of the evidence influenced both probability and verdict with the former mediating differences in the later. Because probability is only one of the several determinants of the verdict, the two dependent variables are not as closely related as the law presumes. Copyright © 2011 John Wiley & Sons, Ltd.     

Instance‐based Learning: A General Model of Repeated Binary Choice

A common practice in cognitive modeling is to develop new models specific to each particular task. We question this approach and draw on an existing theory, instance‐based learning theory (IBLT), to explain learning behavior in three different choice tasks. The same instance‐based learning model generalizes accurately to choices in a repeated binary choice task, in a probability learning task, and in a repeated binary choice task within a changing environment. We assert that, although the three tasks are different, the source of learning is equivalent and therefore, the cognitive process elicited should be captured by one single model. This evidence supports previous findings that instance‐based learning is a robust learning process that is triggered in a wide range of tasks from the simple repeated choice tasks to the most dynamic decision making tasks. Copyright © 2010 John Wiley & Sons, Ltd.     

How fast can you (possibly) do it,or how long will it (certainly) take? Communicating uncertain estimates of performance time

Recent research on verbal probability statements has revealed that some expressions (e.g., possible) are especially appropriate for describing outcomes in the high end of a distribution, whereas other expressions (e.g., certain) are more appropriate for describing low-end values. However, some dimensions appear to be reversible, with higher achievements sometimes associated with high and sometimes with low values, depending on frame. We report three experiments where this “reframing effect” is studied in communications of estimated performance time, both from a speaker's and from a listener's perspective. We hypothesize that statements describing tasks as “taking time” suggest a duration frame, and find accordingly that statements about how many hours that possibly will be spent on a task, or the time a task possibly takes, lead to high time estimates. Statements focusing on the actor's role suggest, in contrast, a speed frame, thus statements about what the actor can possibly do lead to low time estimates. Estimates of the time a task certainly takes or when it is certainly done follow the opposite pattern. The results are in line with approaches that see production and comprehension of language as a dynamical and context-driven process.