Biomedical subjects

Evan Heit

Publications and source records attributed to Evan Heit.

10 recordsLinked to original sources

PubMed2005

Category content and structure in schizophrenia: an evaluation using the instantiation principle.

In numerous studies, researchers have suggested anomalies in semantics in patients with schizophrenia. In this study, the authors addressed whether one such anomaly might reflect a difference in knowledge content or in the structure or organization of this information. Using a category member production task and a typicality rating task, the authors assessed knowledge content and found that patients' and control participants' knowledge about categories of foods and animals was very similar. In terms of structure, their findings from a mathematical model of category judgment (the instantiation model; E. Heit & L. W. Barsalou, 1996) revealed a similar category structure in patients and control participants. In conclusion, the authors suggest that the content and organization of categories in patients with schizophrenia is similar to that in healthy control participants.

Adult↗

PubMed2005

Relations between premise similarity and inductive strength.

According to the diversity principle, diverse evidence is strong evidence. There has been considerable evidence that people respect this principle in inductive reasoning. However, exceptions may be particularly informative. Medin, Coley, Storms, and Hayes (2003) introduced a relevance theory of inductive reasoning and used this theory to predict exceptions, including the nondiversity-by-property-reinforcement effect. A new experiment in which this phenomenon was investigated is reported here. Subjects made inductive strength judgments and similarity judgments for stimuli from Medin et al. (2003). The inductive strength judgments showed the same pattern as that in Medin et al. (2003); however, the similarity judgments suggested that the pattern should be interpreted as a diversity effect, rather than as a nondiversity effect. It is concluded that the evidence regarding the predicted nondiversity-by-property-reinforcement effect does not give distinctive support for relevance theory, although this theory does address other results.

Culture↗

PubMed2004

Why learning and development can lead to poorer recognition memory.

Current models of inductive reasoning in children and adults assume a central role for categorical knowledge. A recent paper by Sloutsky and Fisher challenges this assumption, showing that children are more likely than adults to rely on perceptual similarity as a basis for induction, and introduces a more direct method for examining the representations activated during induction. This method has the potential to constrain models of induction in novel ways, although there are still important challenges.

Child↗

PubMed2004

Nonmonotonic extrapolation in function learning.

This article reports the results of an experiment addressing extrapolation in function learning, in particular the issue of whether participants can extrapolate in a nonmonotonic manner. Existing models of function learning, including the extrapolation association model of function learning (EXAM; E. L. DeLosh, J. R. Busemeyer, & M. A. McDaniel, 1997), cannot account for this type of extrapolation pattern. We present the results of an experiment in which participants were shown a series of paired stimulus-response magnitudes where the relationship between these 2 dimensions conformed to a cyclic function. Participants were shown to extrapolate from these training data in a nonmonotonic way, contrary to predictions from EXAM. A new model of function learning is presented, which predicts responses more accurately than EXAM.

Cognition↗

PubMed2004

Modeling the effects of prior knowledge on learning incongruent features of category members.

The authors conducted 3 experiments addressing the issue of how observations and multiple sources of prior knowledge are put together in category learning. In Experiments 1 and 2, learning was faster for critical features, which were predictable on the basis of prior knowledge, than for filler features, and this advantage increased as more observations were made. In addition, learning was fastest for incongruent features that could only be predicted using knowledge from other domains. In Experiment 3, presenting contradictory features that violated prior knowledge led to rote learning rather than use of prior knowledge. The results were simulated with the Baywatch model, which addresses how observations of category members lead to recruitment and selection of sources of prior knowledge.

Cognition↗

PubMed2004

Strategic processes in false recognition memory.

In two experiments, the response signal technique (Reed, 1973) was combined with the DRM paradigm (e.g., McDermott & Roediger, 1998) to investigate the time course of false recognition memory--in particular, how this effect varies along the time course of generating a recognition judgment. Across the experiments, in addition to standard instructions, there were forewarning instructions encouraging the participants to avoid this effect, as well as inclusion instructions intended to enhance this tendency. It was found that the false memory effect was at its strongest at earlier response signals, diminishing when more time was given to make a recognition judgment. The forewarning instructions led to a more conservative overall response bias, rather than to a reduction of the effect. However, the participants were able to exaggerate this effect in the inclusion condition. The results are discussed in terms of the role of strategic processing in recognition memory.

Humans↗

PubMed2003

The role of diverse instruction in conceptual change.

This study examined how a fundamental principle of induction and scientific reasoning, information diversity, could be used to promote change in children's mental models of the earth's shape. Six-year-old children (N=132) were randomly allocated to a control or to one of two training conditions. Some training groups received instruction that simultaneously challenged children's beliefs concerning (a) why the earth appears flat to a surface observer and (b) the role of gravity. Others received instruction that repeatedly challenged only one of these beliefs. An adaptation of the Vosniadou and Brewer (1992, Cognitive Psychology 24, 535-585) protocol for identifying mental models of the earth was administered before and after instruction. Both instruction methods produced increases in factual knowledge. Only children receiving instruction about two core beliefs, however, showed an increased rate of acceptance of a spherical earth model at posttest. The findings show that instruction that challenges diverse aspects of children's naïve scientific beliefs is more likely to produce conceptual change.

Child↗

PubMed2003

Feature-sampling and random-walk models of individual-stimulus recognition.

Traditional process models of old-new recognition have not addressed differences in accuracy and response time between individual stimuli. Two new process models of recognition are presented and applied to response time and accuracy data from 3 old-new recognition experiments. The 1st model is derived from a feature-sampling account of the time course of categorization, whereas the 2nd model is a generalization of a random-walk model of categorization. In the experiments, a new technique was used, which yielded reliable individual-stimulus data through repeated presentation of structurally equivalent items. The results from the experiments showed reliable differences in accuracy and response times between stimuli. The random-walk model provided the better account of the results from the 3 experiments. The implications of the results for process models of recognition are discussed.

Adult↗

PubMed2003

Adaptive changes of response criterion in recognition memory.

An experiment was conducted to investigate people's ability to vary a response criterion strategically, in a recognition memory task, as a function of the length of time given to process the test stimuli (from 100 to 1,500 msec). The experiment used the response signal procedure, in which the participants responded after a signal that came at a variable time delay from stimulus onset. The proportion of new versus old test items was varied systematically with the time of the response signal, with the proportion of new test items rising, falling, or staying constant at later signals. It was found that the participants' response biases changed adaptively, becoming more conservative at later signals in the rising condition, becoming less conservative in the falling condition, and not changing significantly in the constant condition. Theoretical and methodological implications for recognition memory research are discussed.

Adaptation, Psychological↗

PubMed2002

Perceptual processes in matching and recognition of complex pictures.

The role of perceptual feature sampling in speeded matching and recognition was explored in 4 experiments. Experiments 1-3 involved a perceptual matching task with pictures of various objects and scenes. In Experiments 2 and 3, same-different judgments were given under time pressure. The main objective of the matching task was to obtain measures of the perceptual processing rates of different object features. Experiment 4 was an old-new recognition experiment, in which the same stimuli as those in the matching task were used. Response signals were used to limit processing time in the recognition task. The results demonstrated that it is possible to predict speeded recognition performance from performance in perceptual matching. A simple stochastic feature-sampling model provides a unified account of the data from the 4 experiments.

Analysis of Variance↗