Event-related potentials reveal the relations between feature representations at different levels of abstraction.

In this paper, we use behavioural methods and event-related potentials (ERPs) to explore the relations between informational and instantiated features, as well as the relation between feature abstraction and rule type. Participants are trained to categorize two species of fictitious animals and then identify perceptually novel exemplars. Critically, two groups are given a perfectly predictive counting rule that, according to Hannah and Brooks (2009. Featuring familiarity: How a familiar feature instantiation influences categorization. Canadian Journal of Experimental Psychology/Revue Canadienne de Psychologie Expérimentale, 63, 263-275. Retrieved from http://doi.org/10.1037/a0017919), should orient them to using abstract informational features when categorizing the novel transfer items. A third group is taught a feature list rule, which should orient them to using detailed instantiated features. One counting-rule group were taught their rule before any exposure to the actual stimuli, and the other immediately after training, having learned the instantiations first. The feature-list group were also taught their rule after training. The ERP results suggest that at test, the two counting-rule groups processed items differently, despite their identical rule. This not only supports the distinction that informational and instantiated features are qualitatively different feature representations, but also implies that rules can readily operate over concrete inputs, in contradiction to traditional approaches that assume that rules necessarily act on abstract inputs.

On-the-fly scheduling as a manifestation of partial-order planning and dynamic task values.

OBJECTIVE: The aim of this study was to develop a computational account of the spontaneous task ordering that occurs within jobs as work unfolds ("on-the-fly task scheduling"). BACKGROUND: Air traffic control is an example of work in which operators have to schedule their tasks as a partially predictable work flow emerges. To date, little attention has been paid to such on-the-fly scheduling situations. METHOD: We present a series of discrete-event models fit to conflict resolution decision data collected from experienced controllers operating in a high-fidelity simulation. RESULTS: Our simulations reveal air traffic controllers' scheduling decisions as examples of the partial-order planning approach of Hayes-Roth and Hayes-Roth. The most successful model uses opportunistic first-come-first-served scheduling to select tasks from a queue. Tasks with short deadlines are executed immediately. Tasks with long deadlines are evaluated to assess whether they need to be executed immediately or deferred. CONCLUSION: On-the-fly task scheduling is computationally tractable despite its surface complexity and understandable as an example of both the partial-order planning strategy and the dynamic-value approach to prioritization.

Age differences in contingency judgement linked to perceptual segregation.

We demonstrate large differences in judging positive and null contingencies between younger and older adults with a task commonly used to explore cue competition in both contingency and causality judgements. The one-phase blocking task uses two cues, with separate contingencies with the same outcome. The age differences persisted even when participants knew in advance which of the two contingencies to judge. The age differences disappeared, however, when the stimulus display contained markers aiding perceptual segregation. We suggest that the age differences elicited in the one-phase blocking task are linked to decrements in perceptual segregation.

An instance theory of associative learning.

We present and test an instance model of associative learning. The model, Minerva-AL, treats associative learning as cued recall. Memory preserves the events of individual trials in separate traces. A probe presented to memory contacts all traces in parallel and retrieves a weighted sum of the traces, a structure called the echo. Learning of a cue-outcome relationship is measured by the cue's ability to retrieve a target outcome. The theory predicts a number of associative learning phenomena, including acquisition, extinction, reacquisition, conditioned inhibition, external inhibition, latent inhibition, discrimination, generalization, blocking, overshadowing, overexpectation, superconditioning, recovery from blocking, recovery from overshadowing, recovery from overexpectation, backward blocking, backward conditioned inhibition, and second-order retrospective revaluation. We argue that associative learning is consistent with an instance-based approach to learning and memory.

The criterion-calibration model of cue interaction in contingency judgments.

Siegel, Allan, Hannah, and Crump (2009) demonstrated that cue interaction effects in human contingency judgments reflect processing that occurs after the acquisition of information. This finding is in conflict with a broad class of theories. We present a new postacquisition model, the criterion-calibration model, that describes cue interaction effects as involving shifts in a report criterion. The model accounts for the Siegel et al. data and outperforms the only other postacquisition model of cue interaction, Stout and Miller's (2007) SOCR model. We present new data from an experiment designed to evaluate a prediction of the two models regarding reciprocal cue interaction effects. The new data provide further support for the criterion-calibration model.

A memory-based account of retrospective revaluation.

We adapt an instance model of human memory, Minerva 2, to simulate retrospective revaluation. In the account, memory preserves the events of individual trials in separate traces. A probe presented to memory contacts all traces in parallel and causes each to become active. The information retrieved from memory is the sum of the activated traces. Learning is modelled as a process of cued-recall; encoding is modelled as a process of differential encoding of unexpected features in the probe (i.e., expectancy-encoding). The model captures three examples of retrospective revaluation: backward blocking, recovery from blocking, and backward conditioned inhibition. The work integrates an understanding of human memory and complex associative learning.

Featuring familiarity: how a familiar feature instantiation influences categorization.

We demonstrate that a familiar looking feature can influence categorization through 2 different routes, depending on whether a person is reliant on abstract feature representations or on concrete feature representations. In 2 experiments, trained participants categorized new category members in a 3-step procedure: Participants made an initial categorization, described the rule-consistent features indicated by the experimenter, and then recategorized the item. Critical was what happened on the second categorization after participants initially categorized an item based on a familiar, but misleading, feature. Participants who were reliant on abstract features most commonly reversed themselves after the rule-consistent features were pointed out, suggesting that the familiar feature had biased attention. Participants who were reliant on concrete feature representations, however, most commonly persisted with the initial response as if the familiar feature were more important than its rivals-the familiar feature biased decision making.

Cue-interaction effects in contingency judgments using the streamed-trial procedure.

The authors previously described a procedure that permits rapid, multiple within-participant assessments of the contingency between a cue and an outcome (the "streamed-trial" procedure, Crump, Hannah, Allan, & Hord, 2007). In the present experiments, the authors modified this procedure to investigate cue-interaction effects, replicating conventional findings in both the one- and two-phase blocking paradigms. The authors show that the streamed-trial procedure is not restricted to the geometric forms used as cues and outcomes by Crump et al., and that it can incorporate the conventional allergy stimuli, where food is the cue and an allergic reaction is the outcome. The authors discuss the value of the streamed-trial procedure as a method for advancing our theoretical understanding of cue-interaction effects.

Just tell me what to do: bringing back experimenter control in active contingency tasks with the command-performance procedure and finding cue density effects along the way.

Active contingency tasks, such as those used to explore judgments of control, suffer from variability in the actual values of critical variables. The authors debut a new, easily implemented procedure that restores control over these variables to the experimenter simply by telling participants when to respond, and when to withhold responding. This command-performance procedure not only restores control over critical variables such as actual contingency, it also allows response frequency to be manipulated independently of contingency or outcome frequency. This yields the first demonstration, to our knowledge, of the equivalent of a cue density effect in an active contingency task. Judgments of control are biased by response frequency outcome frequency, just as they are also biased by outcome frequency.

The psychophysics of contingency assessment.

The authors previously described a procedure that permits rapid, multiple within-participant evaluations of contingency assessment (the "streamed-trial" procedure, M. J. C. Crump, S. D. Hannah, L. G. Allan, & L. K. Hord, 2007). In the present experiments, they used the streamed-trial procedure, combined with the method of constant stimuli and a binary classification response, to assess the psychophysics of contingency assessment. This strategy provides a methodology for evaluating whether variations in contingency assessment reflect changes in the participant's sensitivity to the contingency or changes in the participant's response bias (or decision criterion). The sign of the contingency (positive or negative), outcome density, and imposition of an explicit payoff structure had little influence on sensitivity to contingencies but did influence the decision criterion. The authors discuss how a psychophysical analysis can provide a better understanding of findings in the literature such as mood and age effects on contingency assessment. They also discuss the relation between a psychophysical approach and an associative account of contingency assessment.

Contingency judgements on the fly.

The present research was conducted to establish the validity of a novel procedure for measuring human contingency judgements aimed at shortening the length of conventional procedures. Cues and outcomes were simple geometric shapes that were presented in a rapid streaming fashion, reducing the length of a block of trials from several minutes to a few seconds. We establish the reliability of the procedure by replicating two central findings in the contingency judgement literature, and we elaborate on the importance of this method for future research.

Producing biased diagnoses with unambiguous stimuli: The importance of feature instantiations.

In this article, the authors demonstrate a laboratory analogue of medical diagnostic biasing (V. R. LeBlanc, G. R. Norman, & L. R. Brooks, 2001) in 2 experiments and explore the basis of this effect. Before categorizing novel exemplars, participants first evaluated the likelihood that the item was a member of the category suggested on that trial: either the correct category or a plausible alternative category. This was sufficient to produce a substantial bias toward the suggested category despite the use of unambiguous stimuli, explicit rules, and unhurried conditions--each of which would be likely to limit diagnostic bias. The authors argue that the production of this effect requires distinguishing between particular feature instantiations and more abstract representations of those features as well as allowing people to adopt a particular decision strategy mediating the use of instantiated features: a feature-recognition heuristic.

Instantiated features and the use of "rules.".

Classification "rules" in expert and everyday discourse are usually deficient by formal standards, lacking explicit decision procedures and precise terms. The authors argue that a central function of such weak rules is to focus on perceptual learning rather than to provide definitions. In 5 experiments, transfer following learning of family resemblance categories was influenced more by familiar-appearing features than by novel-appearing features equally acceptable under the rule. This occurred both when rules were induced and when rules were given at the beginning of instruction. To model this and other phenomena in categorization, features must be represented on 2 levels: informational and instantiated. These 2 feature levels are crucial to provide broad generalization while reflecting the known peculiarities of a complex world.