From the lab to the police station. A successful application of eyewitness research

The U.S. Department of Justice released the first national guide for collecting and preserving eyewitness evidence in October 1999. Scientific psychology played a large role in making a case for these procedural guidelines as well as in setting a scientific foundation for the guidelines, and eyewitness researchers directly participated in writing them. The authors describe how eyewitness researchers shaped understanding of eyewitness evidence issues over a long period of time through research and theory on system variables. Additional pressure for guidelines was applied by psychologists through expert testimony that focused on deficiencies in the procedures used to collect the eyewitness evidence. DNA exoneration cases were particularly important in leading U.S. Attorney General Janet Reno to notice the eyewitness literature in psychology and to order the National Institute of Justice to coordinate the development of national guidelines. The authors describe their experience as members of the working group, which included prosecutors, defense lawyers, and law enforcement officers from across the country.     

Knowledge central: A central role for knowledge attributions in social evaluations

Five experiments (N?=?1710) demonstrate the central role of knowledge attributions in social evaluations. In Experiments 1–3, we manipulated whether an agent believes, is certain of, or knows a true proposition and asked people to rate whether the agent should perform a variety of actions. We found that knowledge, more so than belief or certainty, leads people to judge that the agent should act. In Experiments 4–5, we investigated whether attributions of knowledge or certainty can explain an important finding on how people act based on statistical evidence, known as “the Wells effect”. We found that knowledge attributions, but not certainty attributions, mediate this effect on decision making.     

A central circuit of the mind

The methodologies of cognitive architectures and functional magnetic resonance imaging can mutually inform each other. For example, four modules of the ACT-R (adaptive control of thought - rational) cognitive architecture have been associated with four brain regions that are active in complex tasks. Activity in a lateral inferior prefrontal region reflects retrieval of information in a declarative module; activity in a posterior parietal region reflects changes to problem representations in an imaginal module; activity in the anterior cingulate cortex reflects the updates of control information in a goal module; and activity in the caudate nucleus reflects execution of productions in a procedural module. Differential patterns of activation in such central regions can reveal the time course of different components of complex cognition.     

Learning disabilities and central nervous system involvement.

The relation of damage to the central nervous system to learning disabilities remains a continuing issue. This study explored how learning disable children fare on the Visual Retention Test. Analysis of correct scores and errors for the 24 children responding to Administration A would ordinarily suggest a primary relationship (t = 2.60, p less than .02; t = 4.01, p less than .001, respectively). However, since extensive medical and case history material yielded no evidence of cerebral injury or disease and since the impact of short-term memory (Administration D) led to no further performance decrement (t less than 1.00), additional research must determine a more precise understanding of perceptual dysfunction and the role of short-term memory in regard to learning disabilities.     

A central capacity sharing model of dual-task performance

The authors present the central capacity sharing (CCS) model and derive equations describing its behaviors to explain results from dual-task situations. The predictions of the CCS model are contrasted with those of the central bottleneck model. The CCS model predicts all of the hallmark effects of the psychological refractory period (PRP) pardigm: -1 slope of the PRP effect at short stimulus onset asynchronies (SOAs), underadditivity of precentral Task 2 manipulations, additivity of central or postcentral Task 2 manipulations with SOA, and carry forward to Task 2 of Task 1 precentral or central manipulations at short SOAs. The CCS model also predicts that Task 1 response times increase with decreasing SOA. The model is a viable alternative to the central bottleneck model.     

Protective inhibition: A central factor in auditory fatigue

Summary A signal detection experiment was performed to investigate the sensitivity shift after stimulation with discontinuous octave-band noise of 95 dB (A). The influence of psychological factors on the sensitivity shift in the stimulated and the unstimulated ear was investigated in a two-factorial experimental design. In four independent groups of 12 Ss each, the psychological meaning of the noise and the side of sensitivity measurement were varied. Half of the Ss listened passively to the noise stimuli (control groups), the other half was made to believe that the noise signaled errors in a tracking task (experimental groups). After exposure of noise stimuli to the right ear the sensitivity of either the right or the left ear was determined. After exposure to noise the sensitivity of the stimulated ear was shown to be significantly more reduced in the experimental than in the control group. Thus, depending on the meaning of the noise physically identical stimuli produce sensitivity shifts of different amounts. After stimulation of the right ear with noise the sensitivity of the left ear remained completely unaffected. The sensitivity shift of the right ear did not persist as long as a threshold shift would have done. The hypothesis is that intensive auditory stimuli will produce negative feedback which protects — within certain limits — the stimulated ear from the fatiguing after-effects of overstimulation. The effectiveness of this protective inhibition depends on psychological factors.We are grateful to S. Jörg-Wagner for his competent handling of the experiment.     

The central role of the parietal lobes in consciousness.

There are now various approaches to understand where and how in the brain consciousness arises from neural activity, none of which is universally accepted. Difficulties among these approaches are reviewed, and a missing ingredient is proposed here to help adjudicate between them, that of "perspectivalness." In addition to a suitable temporal duration and information content of the relevant bound brain activity, this extra component is posited as being a further important ingredient for the creation of consciousness from neural activity. It guides the development of what is termed the "Central Representation," which is supposed to be present in all mammals and extended in humans to support self-consciousness as well as phenomenal consciousness. Experimental evidence and a theoretical framework for the existence of the central representation are presented, which relates the extra component to specific buffer working memory sites in the inferior parietal lobes, acting as attentional coordinators on the spatial maps making up the central representation. The article closes with a discussion of various open questions.     

Cardiovascular reactivity and central adiposity in older African Americans.

This study examined central adiposity, as measured by waist circumference (WC), in relation to mental-stress induced systolic (SBP) and diastolic blood pressure (DBP) and heart rate (HR) responses, body composition, the metabolic syndrome, and health practices in 22 older, African American men and women (ages 52-79 years). The high WC (> 100 cm) group showed significantly greater SBP, DBP, and HR reactivity, greater fasting insulin levels, lower high density lipoprotein cholesterol levels, greater fat mass in both truncal and peripheral regions, and greater body mass index as compared to the low WC (< 100 cm) group. Groups were comparable with respect to fat-free mass, peak oxygen consumption (VO2), leisure time activity, dietary intake, resting blood pressure, and other metabolic variables. The findings support a clustering of metabolic and mental stress risk factors that may predispose older African Americans to increased cardiovascular and metabolic disease.     

A central performance drop with luminance stimuli requiring spatial integration

This study reports four experiments that analyzed detection performance for luminance contrasts as a function of retinal eccentricity in order to find further support and explanations for the central performance drop (CPD) in the fovea. In the first experiment, 10 participants (16-37 years of age) had to detect a target patch in a stimulus consisting of bright and dark pixels. Luminance differences between target and context areas were achieved by placing a different number of bright (and dark) pixels in the target and the context area. Results showed a marked CPD; that is, performance did not peak in the fovea but in the parafovea. A spatial integration hypothesis was proposed to explain this CPD. Alternative explanations were tested in three further experiments with a total of 28 participants from 19-46 years of age (using the decision criterion effect, the selective masking effect, and inhibition by high frequencies). The findings did not contradict the spatial-integration hypothesis.     

A multinomial model to assess central characteristics of mental operators

Knowledge about potential operators, about the preconditions of their applicability, and about their effects is essential to interact effectively with the physical world. Four classes of representational units of this knowledge can be distinguished: I) rules, II) structures, III) instances, and IV) episodes. Two important characteristics of these units are the abstractness of content and the directionality of access. A multinomial model is presented that enables the measurement of these characteristics. Three experiments were conducted to validate the parameters of the model. The multinomial model could be fitted very well to the empirical data of each experiment. Moreover, the parameter estimates showed the expected effects. The model allows the investigation of the influence of important variables (for example, knowledge domain, type of instruction, or amount of practice) on characteristics of mental operators without a strong commitment to any specific process theory. Debates regarding the contribution of different kinds of knowledge can be converted into statistical tests of the corresponding model parameters.     

The bimean: A measure of central tendency that accommodates outliers

Observations that depart considerably from the center of a distribution demand special consideration. They may be retained, trimmed, or weighted less than other data. This article provides a BASIC program that implements Mosteller and Tukey’s (1977) technique for weighting observations less as they depart from the middle of a distribution. Influence curves for this “bisquare-weighted mean,” or “bimean,” are displayed and compared with more traditional measures of central tendency.