Conceptual interrelatedness and caricatures

Concepts are interrelated to the extent that the characterization of each concept is influenced by the other concepts, and are isolated to the extent that the characterization of one concept is independent of other concepts. The relative categorization accuracy of the prototype and caricature of a concept can be used as a measure of concept interrelatedness. The prototype is the central tendency of a concept, whereas a caricature deviates from the concept's central tendency in the direction opposite the central tendency of other acquired concepts. The prototype is predicted to be relatively well categorized when a concept is relatively independent of other concepts, but the caricature is predicted to be relatively well categorized when a concept is highly related to other concepts. Support for these predictions comes from manipulations of the labels given to simultaneously acquired concepts (Experiment 1) and of the order of categories during learning (Experiment 2).     

On the generality of optimal versus objective classifier feedback effects on decision criterion learning in perceptual categorization

Biased category payoff matrices engender separate reward- and accuracy-maximizing decision criteria Although instructed to maximize reward, observers use suboptimal decision criteria that place greater emphasis on accuracy than is optimal. In this study, objective classifier feedback (the objectively correct response) was compared with optimal classifier feedback (the optimal classifier's response) at two levels of category discriminability when zero or negative costs accompanied incorrect responses for two payoff matrix multiplication factors. Performance was superior for optimal classifier feedback relative to objective classifier feedback for both zero- and negative-cost conditions, especially when category discriminability was low, but the magnitude of the optimal classifier advantage was approximately equal for zero- and negative-cost conditions. The optimal classifier feedback performance advantage did not interact with the payoff matrix multiplication factor. Model-based analyses suggested that the weight placed on accuracy was reduced for optimal classifier feedback relative to objective classifier feedback and for high category discriminability relative to low category discriminability. In addition, the weight placed on accuracy declined with training when feedback was based on the optimal classifier and remained relatively stable when feedback was based on the objective classifier. These results suggest that feedback based on the optimal classifier leads to superior decision criterion learning across a wide range of experimental conditions.     

Is there a “strength effect” in automatic semantic priming?

According to spreading activation models of automatic priming, highly related associates should yield stronger priming effects than weakly related associates. The strength of relations is usually based on word association norms. However, this strength effect has been found in some studies but not in others. The present study suggests that one factor that might be responsible for this inconsistency is whether the weak associate is the primary or nonprimary response in the word association norms This possibility was explored by comparing priming effects of weak nonprimary and primary associates with those of strong primary associates. Comparable priming effects were found for the strong and weak primary associates whereas the weak nonprimary associates did not yield any priming effects. These results were obtained both in paired (Experiment 1) and single (Experiment 2) presentation priming procedures. Thus, the rank of the associate is an important factor in predicting the magnitude of the priming effect.     

Task-set reconfiguration with predictable and unpredictable task switches

Participants switched frequently between high/low and odd/even classification of a digit. The interval between a task cue and the next digit varied between blocks. In Experiment 1, the task switched predictably every two, four, or eight trials. In Experiment 2, switching predictably every four trials was compared with random switching. With predictable switching, the cost was limited to the first trial of a run. Random switching produced a more gradual approach to asymptotic performance. After one performance, control processes attenuate the resulting change in task-set bias if a further switch is likely, but this strategic modulation is soon overwhelmed by task-set priming through further performances. Preparation reduced switch costs but not interference from the irrelevant attribute: Control of interference appears to be reactive, not proactive. Switch costs did not increase with run length, suggesting that retrieval of the task set last associated with the stimulus did not contribute to switch costs.     

Assessing absentmindedness: Prospective memory complaint and impairment in middle-aged adults

In two experiments, metamemorial differences between prospective and retrospective memory performance were examined. Participants in Experiment 1 were recruited through newspaper advertisements and comprised middle-aged women who experienced exceptional problems in prospective remembering. Experiment 2 involved self-reporters and nonreporters of retrospective memory problems, who were selected from a large population-based sample of middle-aged adults. In both experiments, memory performance was assessed by using a variety of tasks, including five retrospective memory tasks and three prospective memory tasks that varied in level of realism and retrieval support. In both experiments, there were selective differences in memory performance, so that participants who experienced (retrospective or prospective) memory problems showed impaired performance in prospective, but not in retrospective, memory tasks. These findings suggest that memory for future intentions provides a more sensitive task criterion than does memory for past events for assessing individual differences in self-reports of episodic memory problems. Task-specific differences in reliance on frontally mediated executive processes might underlie these differences.     

The word frequency effect for recognition memory and the elevated-attention hypothesis

Empirical tests were conducted on the elevated-attention hypothesis that low-frequency (LF) words are better recognized than high-frequency (HF) words because LF words attract more attention than do HF words (e.g., Glanzer & Adams, 1990). The elevated-attention hypothesis predicts that the hit rate advantage for LF words should be reduced by increases in attentional strain at study. We first tested this prediction in two experiments by varying the amount of experimenter-controlled study time (on the basis of the assumption that a decrease in study time would reduce the amount of resources available for studying a word). The elevated-attention hypothesis was confirmed, but only when words were studied for relatively short durations. This finding led us to formulate an early-phase elevated-attention hypothesis that proposes that more attentional resources are allocated to LF words than to HF words only during the early phase of encoding (which produces the LF hit rate advantage in subsequent recognition) and that the allocation of attentional resources during the late phase of encoding is not greater for LF words than for HF words. An additional empirical test of this revised hypothesis was conducted: Experimenter-controlled study time and the composition of the to-be-remembered pairs of words were varied orthogonally. The results confirmed the early-phase elevated-attention hypothesis.     

Disrupting attention: The need for retrieval cues in working memory theories

Sometimes in conversation, something is said that causes us to want to comment, but before our impending but implicit thoughts can be expressed, the conversation is disrupted. Later, we cannot recall what we wanted to say, but still later, we can. We used the extralist cuing task to model this phenomenon, and across experiments we varied the strength, direction, and directness of the relationship between the retrieval cues and the targeted information. Disruption was varied by switching attention to a different task before testing and by changing the testing context. Such disruptions reduced recall for the target and its implicitly activated memories. Following a disruption, stronger cues that were related to the target or to both the target and its implicit memories were more effective than those that were related to implicit memories. The findings were consistent with a model of long-term working memory that attributes forgetting to a loss of access to what has been activated, which loss is relative to the strength of the retrieval cue. Decay alone does not explain the results, indicating that many models of working memory need to be revised to take the nature of retrieval cues into account.     

Bias in exponential and power function fits due to noise: Comment on Myung,Kim, and Pitt

Myung, Kim, and Pitt (2000) demonstrated that simple power functions almost always provide a better fit to purely random data than do simple exponential functions. This result has important implications, because it suggests that high noise levels, which are common in psychological experiments, may cause a bias favoring power functions. We replicate their result and extend it by showing strong bias for more realistic sample sizes. We also show that biases occur for data that contain both random and systematic components, as may be expected in real data. We then demonstrate that these biases disappear for two- or three-parameter functions that include linear parameters (in at least one parameterization). Our results suggest that one should exercise caution when proposing simple power and exponential functions as models of learning. More generally, our results suggest that linear parameters should be estimated rather than fixed when one is comparing the fit of nonlinear models to noisy data.     

Perceptual completion and object-based representations in short-term visual memory

Object-based representations in visual short-term memory (VSTM) were examined using a change detection memory task. A display comprising two rows of four differently colored elements was followed by a probe display in which only one of the rows reappeared. On same trials, the probed row was identical to the corresponding row in the memory display. On different trials, two of the elements in the probed row had their colors exchanged. In each memory display, a task-irrelevant visual element appeared between the two rows, with the potential to function as an occluder. Performance was enhanced when perceptual completion meant that four, rather than eight, objects were perceived in the memory display and when the probe display revealed that the occluded elements continued behind the occluder. It appears that several forms of representation can co-occur to support VSTM, one of which is object based.     

Belief and recollection of autobiographical memories

In three experiments, undergraduates rated autobiographical memories on scales derived from existing theories of memory. In multiple regression analyses, ratings of the degree to which subjects recollected (i.e., relived) their memories were predicted by visual imagery, auditory imagery, and emotions, whereas ratings of belief in the accuracy of their memories were predicted by knowledge of the setting. Recollection was predicted equally well in between- and within-subjects analyses, but belief consistently had smaller correlations and multiple regression predictions between subjects; individual differences in the cognitive scales that we measured could not account well for individual differences in belief. In contrast, measures of mood (Beck Depression Index) and dissociation (Dissociative Experience Scale) added predictive value for belief, but not for recollection. We also found that highly relived memories almost always had strong visual images and that remember/know judgments made on autobiographical memories were more closely related to belief than to recollection.