Concreteness and item-to-list context associations in the free recall of items differing in context variability

Context variability can be defined as the number of preexperimental contexts in which a given concept appears. Following M. Steyvers and K. J. Malmberg's (2003) work, the authors have shown that concepts that are experienced in fewer preexperimental contexts generally are better remembered in episodic memory tasks than concepts that are experienced in a greater number of preexperimental contexts. The purpose of this article is to demonstrate that low context variability confers its memorial advantage because of stronger item-to-list context associations as compared with high context variability. Three experiments that use environmental context changes from study to test demonstrate that the low context variability advantage is eliminated when item-to-list context associations are not available because of environmental changes at test. In addition, the low context variability advantage is eliminated when inward processing at study prevents the formation of item-to-list context associations.     

Is it impossible to inhibit isoluminant items, or does it simply take longer? Evidence from preview search

Visual search can be facilitated when participants receive a preview of half the distractors (the preview benefit in search; Watson & Humphreys, 1997). Donk and Theeuwes (2001) have argued that preview-based benefits are abolished if the display items are isoluminant to a background. This is consistent with the preview benefit being due to onset capture by the new stimuli. In contrast, the present experiments challenge this suggestion and show that preview benefits can occur under isoluminant conditions, providing that they are given enough time to occur. In Experiment 1, we showed that a preview benefit can occur even with isoluminant stimuli, provided that the old items are previewed for a sufficient time. In Experiment 2, we tested and rejected the idea that this advantage is due to low-level sensory fatigue for the preview stimuli. These findings indicate that the preview effect is not caused solely by onset capture.     

Neural modeling and imaging of the cortical interactions underlying syllable production

This paper describes a neural model of speech acquisition and production that accounts for a wide range of acoustic, kinematic, and neuroimaging data concerning the control of speech movements. The model is a neural network whose components correspond to regions of the cerebral cortex and cerebellum, including premotor, motor, auditory, and somatosensory cortical areas. Computer simulations of the model verify its ability to account for compensation to lip and jaw perturbations during speech. Specific anatomical locations of the model's components are estimated, and these estimates are used to simulate fMRI experiments of simple syllable production.     

A contextual interference account of distinctiveness effects in recognition

In this article, we report on two experiments that aimed to shed light on the memorability effect that derives from varying the uniqueness of contextual cues presented at encoding and retrieval. We sought to understand the locus of the recognition advantage for studying and testing words with nominally irrelevant features that are rarely shared with other words ("low-fan" features) as compared with features that are studied with more words ("high-fan" features). Each word was studied with one high-fan feature and one low-fan feature, but only one of the two features was reinstated at test. Recognition judgments were more accurate when the low-fan feature was reinstated than when the high-fan feature was reinstated. The data suggest that encoding cues that suffer from contextual interference negatively affect retrieval and do so by hindering recollection-based processing.     

Neuroprotection and stroke rehabilitation: modulation and enhancement of recovery

Recent advances in research are modifying our view of recovery after nervous system damage. New findings are changing previously held concepts and providing promising avenues for treatment of patients after stroke. This review discusses mechanisms of neuronal injury after brain ischemia and the attempts to study neuroprotection options based on such mechanisms. It also considers measures available at present to improve outcome after stroke and presents new areas of research, particularly stimulation techniques, neurogenesis and trophic factors to enhance recovery. In order to improve outcomes, medications that may be detrimental to recovery should be avoided, while symptomatic therapy of problems such as depression, pain syndromes and spasticity may contribute to better results. Continued surveillance and early treatment of complications associated with acute stroke, along with supportive care remain the mainstay of treatment for stroke patients in the recovery phase. Present research on limiting brain damage and improving recovery and plasticity enhance the prospects for better clinical treatments to improve recovery after stroke.     

An examination of two-process theories of false recognition

Contemporary theories of false memory suggest there are two processes that combine to produce false memory: one that increases false memory (error-inflating processes) and one that counteracts false memory (error-editing processes). Two experiments using the DRM paradigm (Deese, 1959; Roediger & McDermott, 1995) explored the influence of manipulating the number of associates studied, study item presentation frequency, backward associative strength, and study time on error-inflating and error-editing processes separately by examining speeded and unspeeded recognition decisions. The results of these studies indicate that (1) increasing the number of associates studied primarily influenced error-inflating processes; (2) increasing backward associative strength increased error-inflating processes and impaired error-editing processes; (3) increasing study item presentation frequency increased both error-inflating and error-editing processes; and (4) increasing study time had a weak effect on error-editing processes. Further, the results of these studies suggest that comprehensive theories of false memory phenomena must propose the existence of two different factors: one that increases false memory and is available early in memory retrieval, and one that usually, but not always, decreases false memory and is available later in retrieval.     

Predicting Individual Score Elevation in an Applicant Setting: The Influence of Individual Differences and Situational Perceptions

Previous research has indicated that applicants can increase their scores on non‐cognitive measures by half of 1 standard deviation (e.g., Rosse, Stecher, Miller, & Levin, 1998 ; Viswesvaran & Ones, 1999 ). Two influential factors have been proposed to influence this elevation: individual differences and situational influences (e.g., Douglas, McDaniel, & Snell, 1996 ). The current study examined how individual differences and motivation (expectancy theory) predicted individual response elevation from a general to a job applicant context using a conscientiousness measure. Results indicated that elevation was primarily predicted by emotional stability, instrumentality, and the interaction between expectancy and instrumentality. Practical implications and future research directions are discussed.     

Distributed recognition of natural songs by European starlings

Individual vocal recognition behaviors in songbirds provide an excellent framework for the investigation of comparative psychological and neurobiological mechanisms that support the perception and cognition of complex acoustic communication signals. To this end, the complex songs of European starlings have been studied extensively. Yet, several basic parameters of starling individual vocal recognition have not been assessed. Here we investigate the temporal extent of song information acquired by starlings during vocal recognition learning. We trained two groups of starlings using standard operant conditioning techniques to recognize several songs from two conspecific male singers. In the first experiment we tested their ability to maintain accurate recognition when presented with (1) random sequences of 1–12 motifs (stereotyped song components) drawn from the training songs, and (2) 0.1–12-s excerpts of continuous song drawn from the training songs. We found that song recognition improved monotonically as more vocal material is provided. In the second experiment, we systematically substituted continuous, varying length regions of white noise for portions of the training songs and again examined recognition accuracy. Recognition remained above chance levels for all noise substitutions tested (up to 91% of the training stimulus) although all but the smallest substitutions led to some decrement in song recognition. Overall, above chance recognition could be obtained with surprisingly few motifs, short excerpts of song, and in the absence of large portions of the training songs. These results suggest that starlings acquire a representation of song during individual vocal recognition learning that is robust to perturbations and distributed broadly over large portions of these complex acoustic sequences.     

A Constrained Linear Estimator for Multiple Regression

“Improper linear models” (see Dawes, Am. Psychol. 34:571–582, 1979), such as equal weighting, have garnered interest as alternatives to standard regression models. We analyze the general circumstances under which these models perform well by recasting a class of “improper” linear models as “proper” statistical models with a single predictor. We derive the upper bound on the mean squared error of this estimator and demonstrate that it has less variance than ordinary least squares estimates. We examine common choices of the weighting vector used in the literature, e.g., single variable heuristics and equal weighting, and illustrate their performance in various test cases.