The simplicity principle in human concept learning

How do we learn concepts and categories from examples? Part of the answer might be that we induce the simplest category consistent with a given set of example objects. This seemingly obvious idea, akin to simplicity principles in many fields, plays surprisingly little role in contemporary theories of concept learning, which are mostly based on the storage of exemplars, and avoid summarization or overt abstraction of any kind. This article reviews some evidence that complexity minimization does indeed play a central role in human concept learning. The chief finding is that subjects' ability to learn concepts depends heavily on the concepts' intrinsic complexity; more complex concepts are more difficult to learn. This pervasive effect suggests, contrary to exemplar theories, that concept learning critically involves the extraction of a simplified or abstracted generalization from examples.     

The contribution of morphological and semantic relatedness to repetition priming at short and long lags: Evidence from hebrew

The effect of morphological repetition at lag 0 and at lag 15 on lexical decision was investigated in Hebrew with three types of relation between prime and target. In the semantic-plus-morphological condition (SM), the prime and the target in each pair were two semantically related derivatives of the same root. In the “pure morphological” condition (M), the prime and the target derived from the same root, but their semantic association was very low, or nonexistent. In the semantic priming condition (S), primes and targets were semantically associated but were not morphologically related. The pure semantic relationship produced a significant facilitation at lag 0 that disappeared completely at lag 15. The pure morphological relation produced (smaller but) significant facilitation at lag 0 that was not attenuated at lag 15. When prime and target were semantically as well as morphologically related, the facilitation at lag 0 was similar to semantic priming, whereas at lag 15 it was similar to the pure morphological effect. Significant repetition effects at both lags were also found with non-words that shared the same (nonsensical) root and differed with respect to real derivational affixes. The differential time course for facilitation due to semantic and morphological relatedness suggests distinct underlying processes, although at lag 0 it is possible that semantic relatedness may augment the morphological repetition effect. Morphological repetition probably facilitates the retrieval of lexical information that, under certain circumstances, is necessary for lexical decision.     

Mispredicting and misremembering: patients with renal failure overestimate improvements in quality of life after a kidney transplant

OBJECTIVE: People tend to overestimate the impact that future events will have on their quality of life. In the case of a medical treatment like kidney transplant, this should result in biased predictions--overestimates of how much the transplant will benefit quality of life. The authors surveyed kidney transplant patients, both before and after transplant, to test whether they would overestimate the benefits of a successful transplant for their quality of life. DESIGN: The authors interviewed 307 patients on a waiting list for cadaveric renal or renal-pancreatic transplant, and 195 patients one year after a successful transplant. A sub sample of patients were interviewed both before and after transplant. MAIN OUTCOME MEASURES: The survey included measures of quality of life, both in terms of an overall estimate (0-100), and across sub domains, including health, employment, and travel. RESULTS: Cross-sectional results suggested that overall quality of life improved after transplant, but the predictions of pretransplant patients overestimated the magnitude of the improvement (p < .01). In addition, patients predicted large improvements in specific life domains that did not change. These results were confirmed in longitudinal, prospective analyses. Additional analyses showed that posttransplant patients recalled their pretransplant quality of life to be much lower than what they had reported at the time. CONCLUSION: Consistent with an impact bias, patients substantially overestimated the benefits of a successful kidney transplant, both in terms of predictions of life after treatment, and in their memories of QOL before the transplant.     

The Generality Problem for Reliabilism

Philosophical Studies -     

Cognitive reference points

Two methods were used to test the hypothesis that natural categories (such as colors, line orientations, and numbers) have reference point stimuli (such as focal colors, vertical and horizontal lines, and numbers that are multiples of 10) in relation to which other stimuli of the category are judged. In Experiment I, subjects placed pairs of stimuli into sentence frames consisting of linguistic “hedges” such as “— is essentially—.” Results were that the supposed reference stimuli were most often placed in the second (reference) slot. In Experiment II, the subject placed a stimulus in physical space to represent his feeling of the psychological distance of that stimulus from another spatially fixed stimulus. Results showed that, when supposed reference stimuli were fixed, other stimuli were placed closer to them than vice versa. The results have substantive implications for the understanding of internal structure of categories and methodological implications for the mapping of reference points, quantification of linguistic intuitions, and the assumption of symmetry in psychological distance judgments.     

A comparison of the thurstone method of multiple factors with the hotelling method of principal components

The factors found by the Hotelling method of principal components present the same necessity for rotation as those found by the Thurstone method of multiple factors.The Thurstone method of multiple factors is here found superior to the Hotelling method of principal components, and is suggested as the method of choice for all problems requiring the determination of elemental components from a group of related variables, since it was found on every point of comparison that, when applied to a correlation matrix of unknown communalities, the Thurstone method was more accurate than the Hotelling method, and also required much less time.