A clarification of self-terminating versus exhaustive variances in serial and parallel models.

A recent study published in Perception & Psychophysics (Donnelly, Found, & Miller, 1999) employs response time (RT) variances (in the form of standard deviations) in addition to mean RTs. Variances can contribute greatly to model testing. However, there is a danger of perpetuating the kinds of logical and methodological errors that have long attended research employing mean RTs alone. This commentary clarifies the theoretical and methodological issues, points out some new results concerning variability in search processes, and indicates how to resolve the global and specific challenges associated with identifying psychological mechanisms.

Multialternative decision field theory: a dynamic connectionist model of decision making.

The authors interpret decision field theory (J. R. Busemeyer & J. T. Townsend, 1993) as a connectionist network and extend it to accommodate multialternative preferential choice situations. This article shows that the classic weighted additive utility model (see R. L. Keeney & H. Raiffa, 1976) and the classic Thurstone preferential choice model (see L. L. Thurstone, 1959) are special cases of this new multialternative decision field theory (MDFT), which also can emulate the search process of the popular elimination by aspects (EBA) model (see A. Tversky, 1969). The new theory is unique in its ability to explain several central empirical results found in the multialternative preference literature with a common set of principles. These empirical results include the similarity effect, the attraction effect, and the compromise effect, and the complex interactions among these three effects. The dynamic nature of the model also implies strong testable predictions concerning the moderating effect of time pressure on these three effects.

Basic response time tools for studying general processing capacity in attention, perception, and cognition.

One of the more important constructs in the study of attention, perception, and cognition is that of capacity. The authors reviewed some of the common meanings of this construct and proposed a more precise treatment. They showed how the distribution of response times can be used to derive measures of process capacity and to further illustrate how these measures can be used to address important hypotheses in cognition.

Spatial frequencies in short-term memory for faces: a test of three frequency-dependent hypotheses.

Spatial frequency manipulations have been shown to have significant utility in ascertaining the various types of information that might be important in object identification and recognition tasks. This utility suggests that, given some mapping between ranges of spatial frequencies and different types of psychological information, it should be possible to examine the roles of these different types of psychological information by way of spatial frequency manipulations. One potential problem, however, is that there is no well-specified, unambiguous mapping between the distinctions in the frequency domain and the distinctions in the informational domain. Three experiments provide tests of three general hypotheses regarding the ways in which different spatial frequencies might map to different information in facial perception and memory tasks: (1) the low-frequency dominance hypothesis, which proposes that low-frequency information should be superior (to high-frequency information) as a cue to perception and memory; (2) the distinct informational roles hypothesis, which holds that high spatial frequencies should carry featural information while low spatial frequencies should carry information about the configuration of those features; and (3) the task-dependent information hypothesis, which suggests that high-frequency information should be best suited to discrimination tasks while low-frequency information should be best suited for recognition tasks. Results generally contradict the first two of these hypotheses, while providing support for the third. Implications with regard to the various issues related to the mapping between spatial frequencies and the informational content of faces, as well as the need to consider important interactions among perceptual and memory processes, are discussed.

Decision field theory: a dynamic-cognitive approach to decision making in an uncertain environment.

Decision field theory provides for a mathematical foundation leading to a dynamic, stochastic theory of decision behavior in an uncertain environment. This theory is used to explain (a) violations of stochastic dominance, (b) violations of strong stochastic transitivity, (c) violations of independence between alternatives, (d) serial position effects on preference, (e) speed-accuracy trade-off effects in decision making, (f) the inverse relation between choice probability and decision time, (g) changes in the direction of preference under time pressure, (h) slower decision times for avoidance as compared with approach conflicts, and (i) preference reversals between choice and selling price measures of preference. The proposed theory is compared with 4 other theories of decision making under uncertainty.

Self-terminating versus exhaustive processes in rapid visual and memory search: an evaluative review.

A major issue in elementary cognition and information processing has been whether rapid search of short-term memory or a visual display can terminate when a predesignated target is found or whether it must proceed until all items are examined. This study summarizes past and recent theoretical results on the ability of self-terminating and exhaustive models to predict differences in slopes between positive (target-present) and negative (target-absent) set-size functions, as well as position effects. The empirical literature is reviewed with regard to the presence of slope differences and position effects. Theoretical investigations demonstrate that self-terminating models can readily predict the results often associated with exhaustive processing, but a very broad class of exhaustive models is incapable of predicting position effects and slope differences typically associated with self-termination. Because position effects and slope differences are found throughout the rapid search literature, we conclude that the exhaustive processing hypothesis is not tenable under common experimental conditions.

Truth and consequences of ordinal differences in statistical distributions: toward a theory of hierarchical inference.

A theory is presented that establishes a dominance hierarchy of potential distinctions (order relations) between two distributions. It is proposed that it is worthwhile for researchers to ascertain the strongest possible distinction, because all weaker distinctions are logically implied. Implications of the theory for hypothesis testing, theory construction, and scales of measurement are considered. Open problems for future research are outlined.

Chemical retention of composite resin to metal.

Three dental adhesives were used to chemically bond three dental veneering resins to a nickel-chromium alloy and a 52% gold alloy. As a control, all three veneering resins were applied directly to the aluminum-oxide-abraded surface without using an adhesive. The various combinations were subjected to a tensile load, and the tensile bond strength and failure location were recorded. The results indicated that the adhesives provided a statistically significant bond between the resin and the alloys.

Experimental test of contemporary mathematical models of visual letter recognition.

A letter confusion experiment that used brief durations manipulated payoffs across the four stimulus letters, which were composed of line segments equal in length. The observers were required to report the features they perceived as well as to give a letter response. The early feature-sampling process is separated from the later letter-decision process in the substantive feature models, and predictions are thus obtained for the frequencies of feature report as well as letter report. Four substantive visual feature-processing models are developed and tested against one another and against three models of a more descriptive nature. The substantive models predict the decisional letter report phase much better than they do the feature-sampling phase, but the best overall 4 X 4 letter confusion matrix fits are obtained with one of the descriptive models, the similarity choice model. The present and other recent results suggest that the assumption that features are sampled in a stochastically independent manner may not be generally valid. The traditional high-threshold conceptualization of feature sampling is also falsified by the frequent reporting by observers of features not contained in the stimulus letter.

Search reaction time for single targets in multiletter stimuli with brief visual displays.

The same set of Ss was run In an LT (single late target letter followed an earher multiletter display) and an ET (single early target preceded a later multiletter display) condition. On one-half the trials, the multiletter set included the target. and on the other half, the target was absent. The task of S was to push the "yes" ("no") button if the target was present (absent), and reaction times were recorded. The most plausible processing model assumed that LT comparisons took place in a verbal-acoustic store and that ET comparisons took place in a visual store. It further assumed that processing within these stores was self-terminating, with rates that differed on "same" and "different" comparisons and which changed as the multiletter set increased. Classes of serial and parallel models that are falsified or supported by the present and similar data are discussed.