"Selective attention and the formation of linear decision boundaries": Erratum.

Reports an error in the original article by S. C. McKinley and R. M. Nosofsky (Journal of Experimental Psychology: Human Perception & Performance, 1996[Apr], Vol 22[2], 294–317). In each row of Table 2, the Akaike's information criterion (AIC) fits for the models are in error by a roughly constant amount. (When calculating the fits, the constant portion of the log-likelihood function that enters into the AIC computation was inadvertently deleted.) The relative AIC fits of the models, the proportion of variance accounted for, as well as all conclusions based on these fits, remains the same. The corrected table appears here. (The following abstract of this article originally appeared in record 1996-03036-003.) Classification experiments were designed to compare the predictions of a linear decision bound model with those of an exemplar-similarity model incorporating an explicit selective attention mechanism. Linear boundaries could account for the data only in tasks involving separable dimension stimuli and where the boundary separating the categories was orthogonal to the psychological dimensions. Linear boundaries provided poor fits to the classification data in situations involving integral dimensions or when the boundary needed to be oriented in oblique directions in the space. The results were consistent with the selection-attention assumptions embodied in the exemplar model. It was argued that similar assumptions about selective attention need to be incorporated within decision bound models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective attention and the formation of linear decision boundaries: Comment on McKinley and Nosofsky (1996).

S. C. McKinley and R. M. Nosofsky (see record 83-21756) compared a linear decision-bound model with the generalized context model (GCM) in their ability to account for categorization data from experiments that used integral- or separable-dimension stimuli and required selective attention or attention to both dimensions. McKinley and Nosofsky found support for the GCM and concluded that decision-bound theory needs to incorporate assumptions about selective attention. In this commentary it is argued that (a) unlike the GCM, decision-bound theory provides a framework for independently investigating perceptual and decisional forms of selective attention; (b) the effect of stimulus integrality on the form of the optimal decision bound is misinterpreted; (c) averaged data is biased against decision-bound theory and toward the GCM; (d) many a priori predictions of the GCM are violated empirically; and (e) exemplar theory has lost much of its initial theoretical structure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigations of exemplar and decision bound models in large, ill-defined category structures.

Experiments involving large-size, ill-defined categories were conducted to distinguish between the predictions of an exemplar model and linear and quadratic decision bound models. In conditions in which the optimal classification boundary was of a more complex form than the quadratic model, the exemplar model provided significantly better accounts of study participants' data than did the decision bound models, even in situations in which a linear bound would have yielded nearly optimal performance. The results suggest that participants are not predisposed or constrained to use linear or quadratic decision bounds for classifying multidimensional perceptual stimuli and that exemplar models may provide a parsimonious process-level account of the complex types of decision bounds used by experiment participants. The results also suggest some limitations on the complexity of the decision bounds that can be learned, in contrast to the predictions of the exemplar model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crystallographic features of intergranular crack initiation in fatigued copper polycrystals

In order to study the mechanism of grain boundary (GB) cracking in fatigued polycrystalline copper, specimens were fatigued in symmetrical push-pull at an intermediate constant plastic strain range at room temperature in dry air. The intergranular cracks were examined under the scanning electron microscope. Many GB cracks were found to have been formed by the impingement of persistent slip bands (PSBs) against the grain boundaries (PSB-GB cracks). The orientations of the grains adjacent to the cracks were determined by electron back-scattering patterns. The misorientations of the cracked boundaries were calculated and the boundary plane orientations were also determined. High-energy grain boundaries were found to be preferred sites for cracking. The activated slip systems in the component grains adjacent to the cracks were determined and analyzed. With these data, the cracking stresses due to the interaction between the PSBs and the boundaries were calculated for the observed PSB-GB cracks in a pile-up type dislocation model in a three-dimensional analysis. The results confirmed that, with reasonable assumptions, the estimated minimum theoretical shear stresses which are required to act in the PSBs for causing PSB-GB cracks were always smaller than the real shear stresses operating in the PSBs.     

The effects of aging on the speed–accuracy compromise: Boundary optimality in the diffusion model.

We evaluated age-related differences in the optimality of decision boundary settings in a diffusion model analysis. In the model, the width of the decision boundary represents the amount of evidence that must accumulate in favor of a response alternative before a decision is made. Wide boundaries lead to slow but accurate responding, and narrow boundaries lead to fast but inaccurate responding. There is a single value of boundary separation that produces the most correct answers in a given period of time, and we refer to this value as the reward rate optimal boundary (RROB). We consistently found across a variety of decision tasks that older adults used boundaries that were much wider than the RROB value. Young adults used boundaries that were closer to the RROB value, although age differences in optimality were smaller with instructions emphasizing speed than with instructions emphasizing accuracy. Young adults adjusted their boundary settings to more closely approach the RROB value when they were provided with accuracy feedback and extensive practice. Older participants showed no evidence of making boundary adjustments in response to feedback or task practice, and they consistently used boundary separation values that produced accuracy levels that were near asymptote. Our results suggest that young adults attempt to balance speed and accuracy to achieve the most correct answers per unit time, whereas older adultts attempt to minimize errors even if they must respond quite slowly to do so. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective Attention Impairments in Alzheimer's Disease: Evidence for Dissociable Components.

Tasks emphasizing 3 different aspects of selective attention-inhibition, visuospatial selective attention, and decision making-were administered to subjects with mild Alzheimer's disease (AD) and to healthy elderly control (HEC) subjects to determine which components of selective attention were impaired in AD subjects and whether selective attention could be dissociated into different components. The tasks were administered with easy versus hard levels of difficulty to assess proportional slowing as the key variable across tasks. The results indicated that the inhibitory and visual search tasks showed greater proportional slowing in subjects with AD than in HEC subjects, and that the task involving inhibition was significantly more affected in subjects with AD. Furthermore, there were no significant intertask correlations, and the results cannot be explained simply in terms of generalized cognitive slowing. These results provide evidence that inhibition is the most strikingly affected aspect of selective attention that is observed to be impaired in early stages of AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual selective attention and reading efficiency are related in children

We investigated the relationship between visual selective attention and linguistic performance. Subjects were classified in four categories according to their accuracy in a letter cancellation task involving selective attention. The task consisted in searching a target letter in a set of background letters and accuracy was measured as a function of set size. We found that children with the lowest performance in the cancellation task present a significantly slower reading rate and a higher number of reading visual errors than children with highest performance. Results also show that these groups of searchers present significant differences in a lexical search task whereas their performance did not differ in lexical decision and syllables control task. The relationship between letter search and reading, as well as the finding that poor readers-searchers perform poorly lexical search tasks also involving selective attention, suggest that the relationship between letter search and reading difficulty may reflect a deficit in a visual selective attention mechanisms which is involved in all these tasks. A deficit in visual attention can be linked to the problems that disabled readers present in the function of magnocellular stream which culminates in posterior parietal cortex, an area which plays an important role in guiding visual attention.     

Boundary issues and multiple relationships: Fantasy and reality.

Psychologists regularly struggle with boundary issues and multiple relationships. Knowing which boundary crossings are acceptable, when a behavior becomes a boundary violation, and which multiple relationships are acceptable and which are not can present great challenges for practicing psychologists. Furthermore, for those who work with diverse populations, these challenges may become even more pronounced. A rational approach to addressing boundaries and multiple relationships is presented along with 4 expert commentaries that further elucidate these issues. Special attention is paid to the role of culture and other diversity factors as they affect how psychologists address boundaries and multiple relationships. Recommendations for ethical and effective practice that incorporate rational decision making and attention to individual differences are made. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantitative modeling of visual attention processes in patients with Parkinson's disease: Effects of stimulus integrality on selective attention and dimensional integration.

Parkinson's disease (PD) patients and normal controls (NCs) were administered a series of visual attention tasks. The dimensional integration task required integration of information from 2 stimulus dimensions. The selective attention task required selective attention to 1 stimulus dimension while ignoring the other stimulus dimension. Both integral- and separable-dimension stimuli were examined. A series of quantitative models of attentional processing was applied to each participant's data. The results suggest that (a) PD patients were not impaired in integrating information from 2 stimulus dimensions, (b) PD patients were impaired in selective attention, (c) selective attention deficits in PD patients were not due to perceptual interference, and (d) PD patients were affected by manipulations of stimulus integrality and separability in much the same way as were NCs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microtexture and grain boundary evolution during microstructural refinement processes in SUPRAL 2004

Electron backscatter pattern (EBSP) analysis of as-processed, processed and annealed, and superplastically deformed specimens of commercially processed SUPRAL 2004 material has been employed to reveal the boundary misorientation distribution and evolution. Earlier studies using X-ray diffraction (XRD) and transmission electron microscopy on this alloy have attributed the transition to microstructures capable of supporting extensive superplastic flow to continuous recrystallization occurring early in the deformation process. The micro- and mesotextural data of the present study show that the deformation texture evident in the as-processed material persists without the formation of recrystallization texture components and remains up to the apparent onset of the grain boundary sliding (GBS) regime. Comparison of the correlated and uncorrelated boundary misorientation data illustrates that the development of boundaries misoriented by ∼5 to 15 deg is not random in nature. There is no evidence of recrystallization involving the formation and migration of high-angle boundaries during the refinement process. Microtextural and boundary data from this study provide evidence that the microstructural transition enabling superplastic mechanical behavior of SUPRAL 2004 may be described by a recovery-dominated, continuous process involving the development of moderately misoriented boundaries and leading to a refined microstructure with a boundary distribution of low interfacial energy character.     

Constrained cavity growth models of longitudinal creep deformation of oxide dispersion strengthened alloys

Two models of constrained cavity growth are developed to describe the long-term longitudinal creep behavior of nickel based oxide dispersion strengthened (ODS) alloys. For both models the rupture time is taken as the time for a transverse grain boundary to cavitate fully. A diffusive cavity growth law is assumed to govern cavitation. The applicability of the respective models is determined by the particular grain morphology achieved by thermal-mechanical processing. The first model assumes that longitudinal grain boundaries are unable to slide; hence displacements due to cavitation must be matched by displacements due to dislocation creep in adjoining grains. This model predicts a low stress exponent at the transition from single crystal to cavitation creep behavior, and higher stress exponents at stresses below this transition. Good agreement is found between the model predictions and creep data for MA 754 at 1000 and 1093 °C. A second model considers a grain morphology wherein longitudinal grain boundaries are able to slide by means of deformation of pockets of fine grains. Cavitation of transverse grain boundaries is thus controlled by grain boundary sliding. This model predicts a stress exponent of 1 at low stresses, and serves as an upper bound for the creep rate when a duplex grain morphology is present. Model predictions are in good agreement with creep data for a heat of MA 754 with a duplex grain morphology. Formerly Graduate Research Assistant in the Department of Materials Science and Engineering at Stanford University     

Attention and learning processes in the identification and categorization of integral stimuli.

Studied the relationship between identification and categorization learning of integral-dimension stimuli within the framework of an exemplar-based generalization model. The model was used to predict learning in 6 different categorization conditions on the basis of data obtained in a single identification learning condition. 34 undergraduates were tested in the identification learning condition and 191 undergraduates were tested in the categorization learning conditions. An assumption in the model is that because of selective attention to component dimensions, similarity relations may change in systematic ways across different experimental contexts. Results indicate that selective attention may play a critical role in determining the identification–categorization relationship for integral stimuli. Similarity among exemplars decreased as a function of identification learning. It is noted that alternative classification models, including prototype, multiple-prototype, average distance, and value-on-dimensions models, were unable to account for the results. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delamination Effect on Flutter of Homogeneous Laminated Plates

The effect of delamination on the flutter boundary of two‐dimensional laminated plates are investigated theoretically. Linear‐plate theory and qusai‐steady aerodynamic theory are employed. A simple beam‐plate‐theory model is developed to predict the flutter boundaries of delaminated homogeneous plates with simply supported ends. The effects of delamination position, size, and thickness on the flutter boundary are studied in detail. The results reveal that the presence of a delamination degraded the stiffness and the natural frequencies of the plate and thereby decreases the flutter boundary of the plate. However, for certain geometries the flutter boundaries were raised due to the flutter coalescence modes of the plate altered by the presence of a delamination in the plate.     

Patterns of ego boundary disturbance in neurotic, borderline, and schizophrenic patients.

As part of a series of articles addressing unresolved conceptual and empirical questions regarding structural diagnosis and the borderline concept, this study examines differences in the representation of interpersonal boundaries among neurotic, borderline, and schizophrenic patients. Drawing on the contributions of Blatt and his colleagues, a Boundary Disturbance Scale was constructed by applying a developmental continuum of boundary representation to a traditional ego psychological analysis of thought disorder on the Rorschach. The results of the study support the hypothesis that severe borderline psychopathology can be conceptualized as a failure to maintain the inner-outer boundary, that schizophrenia involves a deficit in maintaining the distinction between self and others, and that meaningful developmental distinctions between diagnostic groups can be made on the basis of the Rorschach. The findings demonstrate the broad explanatory scope gained by a developmental object relations model in clarifying perplexing diagnostic and conceptual issues involving borderline phenomena on the Rorschach, specifically, (1) the representation of boundaries, (2) the cognitive disturbance involving the inner-outer boundary, and (3) the nature of the short-lived, circumscribed psychotic... (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dislocation and grain boundary interactions in metals

The passage of dislocations through grain boundaries in face centered cubic and body centered cubic polycrystalline metals was studied using dynamic in situ high voltage electron microscopy (HVEM), static transmission electron microscopy (TEM), and anisotropic elastic stress analysis. Several conclusions were reached: (1) when dislocations propagate across grain boundaries, the activated slip system can be predicted from pile-up properties and grain boundary orientation using a combined criterion based on boundary geometric factors and internal stresses; (2) different grain boundaries impede dislocation slip propagation to different degrees, the calculated value of the pile-up obstacle stress varying from 280 to 870 MPa for dislocation transmission through a grain boundary in 304 stainless steel; (3) dynamic in situ straining of miniature tensile specimens reveals additional modes of dislocation and grain boundary interactions that were hidden from static TEM observations. In connection with the last conclusion, simultaneous dislocation transmission and reflection was activated by a stressed pile-up and a complex mechanism involving coordinated movements of four sets of dilocations in and near a grain boundary was observed.     

Individual differences in perceptual information processing and their relation to automobile accident involvement.

Used a perceptual-information-processing model of driver decision making as a framework to select and devise predictors of accident involvement. 75 commercial drivers were tested in a driving simulator and were given the Embedded Figures Test, Selective Attention Test, and rod-and-frame test. The predictors of field dependence, selective attention, and complex reaction time significantly related to accident involvement. Initial, simple, and choice reaction time did not relate to accident rate. The visual measures of field dependence and the auditory measure of selective attention were related in the predicted direction, with the field-independent drivers making fewer errors in selective perception. This finding lends support to the importance of the further development of an information-processing model of the driving task. Since evidence is accumulating that stable individual differences in information processing relate to accident involvement, consideration should be given to devising techniques to develop these skills. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Models of jury decision making: A critical review.

Reviews several models of jury decision making. In each instance the model is described and compared with related models, its assumptions are scrutinized, its fit to normative data is evaluated, and possible revisions and extensions of the model are discussed. Models reviewed include (a) multinomial decision schemes designed to adduce implicit decision rules used in jury decision making; (b) binomial models of jury voting that use simplifying assumptions about jury decision making to assess the impact of explicit decision rules and jury size on verdict distributions; (c) Bayesian models that use normative data to estimate prior probabilities of defendants' "convictability" and juror accuracy; (d) models that assess the relationships among jury size, decision rule, and jury accuracy; (e) models that examine the relationship between juror and jury errors; and (f) a computer simulation that uses simple assumptions about group persuasion and individual differences in jurors' resistance to persuasion to model results from empirical studies of jury decision making. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High temperature creep cavitation mechanisms in a continuously cast high purity copper

Continuously cast high purity copper was used to study intergranular high temperature creep fracture mechanisms. With the help of an internal marker system due to impurity segregation, grain boundary sliding, GBS, was found to have occurred to a similar extent on cavitated and uncavitated boundaries. To explain this phenomenon a void nucleation model involving small nonwetting shearable particles is suggested. Metallographic observations and the apparent activation energy derived from fracture time data indicate the operation of the vacancy condensation mechanism at the lower temperatures and higher stresses. At the higher temperatures and lower stresses void growth is enhanced by GBS. This cavitation mechanism obtains strong support from measurements of the distribution of voids on grain boundaries as a function of the boundary angle with respect to the tensile direction. Computer analysis of these distributions, in terms of a model which properly accounts for the distribution of potential nuclei, yields bimodal curves exhibiting peaks at grain boundaries oriented for high shear stress (peak I), and for high normal stress (peak II). A phenomenological equation is proposed for the dependence of peak I on test conditions. Peak II is thought to be caused by nucleation by local GBS and growth by vacancy condensation under locally enhanced normal stress. A. RUKWIED, formerly Physicist, Engineering Metallurgy Section, Metallurgy Division, National Bureau of Standards, U. S. Department of Commerce, Washington, D. C.