When further learning fails: stability and change following repeated presentation of text.

Kay (1955) presented a text passage to participants on a weekly basis and found that most errors and omissions in recall persisted despite repeated re-presentation of the text. Experiment I replicated and extended Kay's original research, demonstrating that after a first recall attempt there was very little evidence of further learning, whether measured in terms of further acquisition or error correction, over three more presentations of the text passages. Varying the schedule of presentations and tests had little effect, although performance was better when intermediate trials included both presentation and test than when only presentations or tests occurred. Experiment 2 explored whether this 'failure of further learning' effect could be overcome by (a) warning participants against basing their recall on their previous recall efforts and specifically directing them to base their recall upon the passages, (b) making each presentation more distinctive, or (c) drawing participants' attention to areas that would benefit from further learning by requiring them to tally their omissions and errors. The effect persisted in all cases. The findings have serious implications for the learning of text material.

False memories and statistical decision theory: comment on Miller and Wolford (1999) and Roediger and McDermott (1999)

In an analysis of H. L. Roediger and K. B. McDermott's (1995) false-memory paradigm, M. B. Miller and G. L. Wolford (1999) argued that falsely recognized items occur because a bias toward calling such items "old" is created by their membership in a studied category. This interpretation was contested by Roediger and McDermott (1999). The authors of this article approach this issue as a statistical decision problem and observe that an explanation of false memory based on stored strengths and one based on decision process can have identical implications for data. Problems with equivalent formal models of this type can frequently be resolved by looking at the effects of other variables on the fitted estimates. The authors illustrate this analysis by examining the effects of presentation duration on the parameter estimates produced by models that instantiate the 2 explanations. Although the question remains open, the storage-based interpretation was found to be somewhat more plausible.

Paradigm shifts: new techniques to answer new questions.

The advent of a multiple-channels approach to spatial vision 20 years ago raised important questions that were difficult to approach empirically, given the technology and analytic tools of the time. These questions concerned the interaction or combination of different components of a stimulus--questions that have recently resurfaced in more complex form. Classical psychophysical methods for assessing whether two stimulus aspects are coded independently (e.g., masking, adaptation, and cue-summation) provide only limited information about the nature of whatever interactions are discovered. In both older work in detection and recent work in complex pattern discrimination, we have used a double-judgment paradigm in which the observer rates two aspects of a stimulus simultaneously. The paradigm provides a rich source of information about the codes underlying each psychophysical decision and which are unique in permitting us to psychophysically investigate effects resulting from neural noise in the system. Our analyses draw on theories of dimensional interaction in signal detection theory and in information theory, and on methods from several branches of statistics, including categorical data analysis and structural equation modeling. We review the theoretical, technological, methodological, and personal influences that led us to develop this approach.

Categorical data analysis.

This chapter reviews recent developments in the analysis of categorical and contingency-table data. The first portion examines developments in model testing and selection. The second portion examines work on models for the structure of dependence. These include log-linear parameter models, models for latent classes, models for missing observations, numerical-scale-based association and correlation models (such as correspondence analysis), the treatment of ordered categories, and models for marginal distributions.

Discrimination of complex patterns: orientation information is integrated across spatial scale; spatial-frequency and contrast information are not.

Real-world objects are complex, containing information at multiple orientations and spatial scales. It is well established that at initial cortical stages of processing, local information about an image is separately represented at multiple spatial scales. However, it is not yet established how these early representations are later integrated across scale to signal useful information about complex stimulus features, such as edges and textures. In the studies reported here, we investigate the scale-integration processes involved in distinguishing among complex patterns. We use a concurrent-response paradigm in which observers simultaneously judge two components of compound gratings that differ widely in spatial frequency. In different experiments, each component takes one of two slightly different values along the dimensions of spatial frequency, contrast, or orientation. Using analyses developed within the framework of a multivariate extension of signal-detection theory, we ask how information about the frequency, contrast, or orientation of the components is or is not integrated across the two grating components. Our techniques permit us to isolate and identify interactions due to excitatory or inhibitory processes from effects due to noise, and to separately assess any attentional limitations that might occur in processing. Results indicate that orientation information is fully integrated across spatial scales within a limited orientation band and that decisions are based entirely on the summed information. Information about spatial frequency and contrast is not summed over spatial scale; cross-scale results show sensory independence. However, our results suggest that observers cannot simultaneously use information about frequency or contrast when it is presented at different spatial scales. Our results provide direct evidence for the existence of a higher-level summing circuit tailored to signal information about orientation. The properties of this mechanism differ substantially from edge-detector mechanisms proposed by Marr and others.

Signal detection analyses of repetition blindness.

Three experiments used a signal detection model to demonstrate that repetition blindness (N. Kanwisher, 1987) reflects a reduction in sensitivity (d') for the detection of repeated compared with unrepeated visual targets. In experiment 1, repetition blindness (RB) was found for rapid serial visual presentation (RSVP) letter sequences, whether the visual targets were specified by category membership (vowels) or as 1 of 2 prespecified letters (e.g., A or O). In Experiment 2, RB was found to a similar degree even when the Ist critical item was displayed for twice as long as the other list items, although overall performance was considerably improved. Experiment 3 found RB for displays containing just 2 simultaneously presented letters. These results support Kanwisher's (1987) account of RB as a genuine perceptual effect, and rule out alternative accounts of RB as the result of response bias, output interference, or guessing biases.

Dimensions of dysfunctional attitudes as vulnerabilities to depressive symptoms.

Empirical tests of the diathesis-stress component of A. T. Beck's (1976; A. T. Beck, A. J. Rush, B. F. Shaw, & G. Emery, 1979) cognitive theory of depression have generally not yielded positive results. The resulting focus on conceptual and methodological concerns has diverted attention from the more fundamental issue of how validly vulnerability is measured. The present investigation uses the Dysfunctional Attitude Scale (DAS; A. N. Weissman, 1979; A. N. Weissman & Beck, 1978), the most commonly used measure of vulnerability in this area, but adopts a more in-depth approach by examining DAS factors in addition to the typical total score. This study involved a sample of undergraduates who had never before taken a college-level examination. The dimension of the DAS measured by the Perfectionistic Achievement factor had the strongest relationship to increased depressive symptoms in response to poorer-than-expected performance on the examination. Implications for future research in this area are discussed.

The statistical analysis of concurrent detection ratings.

The concurrent detection task is a powerful method for assessing interactions in the processing of two sensory signals. On each trial, a stimulus is presented that is composed of one, both, or neither signal, and the observer makes a detection rating for each stimulus. A classical bivariate signal-detection analysis applies to these data, but is limited by its inability to differentiate certain types of sensory interactions from more cognitive components, and by the lack of an associated testing procedure. The present paper presents an alternative analysis, based on the contingency table of sensory ratings. Six classes of effect can be distinguished and tested: (1) simple response bias, (2) detection of the two signals, (3) interference of each signal on the response to the other signal, (4) sensory and response correlation, (5) bivariate response biases, and (6) higher order association. Complete computational detail is provided.