Visual marking and change detection

The preview benefit from prior exposure of response-irrelevant (distracter) objects in visual search has been accounted for in terms of top-down inhibition (i.e. visual marking), bottom-up abrupt onset capture, or asynchrony-dependent perceptual segregation. We assess the relative contribution of abrupt onset and visual marking in a paradigm combining visual search with a visual working memory task. We investigated time-based selection of multiple objects for storage in visual working memory, using a change detection paradigm (Luck and Vogel in Nature 390:279–281, 1997) with distracter preview. We varied preview exposure (short vs. long), in a series of three experiments. The contribution of asynchrony-related perceptual segregation was assessed across experiments by varying the complexity of the stimuli (colored squares, oriented bars and oriented T-shapes) and the type of change detection (color or orientation), resulting in different levels of perceptual segregation between visual elements. The results suggest that bottom-up abrupt onset, visual marking and perceptual segregation factors co-operate in time-based selection for storage in visual working memory.     

Emotional Word Detection and Adolescent Repressive–Defensive Coping Style

This study used a computer-based emotional word-recognition task to assess the emotional processing styles of repressive–defensive youth. A hypothesis was tested proposing that adolescent repressive–defensive coping style is associated with rapid engagement and disengagement of emotional stimuli (negative and positive). Data were collected on a male adolescent sample enrolled in a juvenile diversion program allowing for the comparison of anxious, low-anxious, and repressive–defensive youth. Consistent with prediction, repressive–defensive participants exhibited facilitated responding to emotional relative to neutral word stimuli across valence category (i.e., positive and negative). In contrast, anxious participants exhibited a unique pattern of facilitated responding to positive word stimuli. The current findings represent a first attempt at investigating the processing impairments of repressive–defensive coping style in a nonadult sample. Results are interpreted in light of broader adult and child research findings on emotional processing and affective disturbance.     

Systems for the Production of Plagiarists? The Implications Arising from the Use of Plagiarism Detection Systems in UK Universities for Asian Learners

This paper argues that the inappropriate framing and implementation of plagiarism detection systems in UK universities can unwittingly construct international students as ‘plagiarists’. It argues that these systems are often implemented with inappropriate assumptions about plagiarism and the way in which new members of a community of practice develop the skills to become full members of that community. Drawing on the literature and some primary data it shows how expectations, norms and practices become translated and negotiated in such a way that legitimate attempts to conform with the expectations of the community of practice often become identified as plagiarism and illegitimate attempts at cheating often become obscured from view. It argues that this inappropriate framing and implementation of plagiarism detection systems may make academic integrity more illusive rather than less. It argues that in its current framing – as systems for ‘detection and discipline’ – plagiarism detection systems may become a new micro-politics of power with devastating consequences for those excluded.     

A theory of attending and reinforcement in conditional discriminations

A model of conditional discrimination performance (Davison & Nevin, 1999) is combined with the notion that unmeasured attending to the sample and comparison stimuli, in the steady state and during disruption, depends on reinforcement in the same way as predicted for overt free-operant responding by behavioral momentum theory (Nevin & Grace, 2000). The rate of observing behavior, a measurable accompaniment of attending, is well described by an equation for steady-state responding derived from momentum theory, and the resistance to change of observing conforms to predictions of momentum theory, supporting a key assumption of the model. When probabilities of attending are less than 1.0, the model accounts for some aspects of conditional-discrimination performance that posed problems for the Davison-Nevin model: (a) the effects of differential reinforcement on the allocation of responses to the comparison stimuli and on accuracy in several matching-to-sample and signal-detection tasks where the differences between the stimuli or responses were varied across conditions, (b) the effects of overall reinforcer rate on the asymptotic level and resistance to change of both response rate and accuracy of matching to sample in multiple schedules, and (c) the effects of fixed-ratio reinforcement on accuracy. Some tests and extensions of the model are suggested, and the role of unmeasured events in behavior theory is considered.     

A note on ROC analysis and non-parametric estimate of sensitivity

In the signal detection paradigm, the non-parametric index of sensitivity A′, as first introduced by Pollack and Norman (1964), is a popular alternative to the more traditional d′ measure of sensitivity. Smith (1995) clarified a confusion about the interpretation of A′ in relation to the area beneath proper receiver operating characteristic (ROC) curves, and provided a formula (which he called A′′) for this commonly held interpretation. However, he made an error in his calculations. Here, we rectify this error by providing the correct formula (which we call A) and compare the discrepancy that would have resulted. The corresponding measure for bias b is also provided. Since all such calculations apply to “proper” ROC curves with non-decreasing slopes, we also prove, as a separate result, the slope-monotonicity of ROC curves generated by likelihood-ratio criterion.This revised article was published online in August 2005 with the PDF paginated correctly.     

Effects of response disparity on stimulus and reinforcer control in human detection tasks

In two detection experiments, university students reported whether the second of two sequentially presented tones was longer or shorter than the first by responding to stimuli presented on a touch screen. Stimulus disparity and response disparity were manipulated to compare their effects on measures of discrimination and response bias when the reinforcement ratio for correct responses was asymmetric. Choice stimuli consisted of squares filled with different pixel densities. Response disparity was manipulated by varying the difference in density between the two choice stimuli. In both experiments, decreasing stimulus disparity reduced discrimination but had no consistent effect on bias. Decreasing response disparity also reduced discrimination in both experiments, and often reduced estimates of bias. The effects of response disparity on bias were most clear in Experiment 2, in which a greater overall level of response disparity was arranged. The data show that, like corresponding research with pigeons, detection performance of human subjects can be conceptualized as discriminated operants.     

测谎中反馈加工的认知神经机制：一项ERP研究

在一个模拟“杀人——侦探”游戏情境中,被试先完成模拟杀人任务,在随后的测谎阶段使用有反馈的ERP测谎范式,以反馈的形式告知被试测谎结果（“+0.5”或“-2”,分别代表“撒谎逃过检测”或“撒谎被发现”）时的脑内时程动态变化。结果发现,在反馈出现后的200～300ms时间段,表示“撒谎被抓住”比“撒谎逃过检测”的反馈信息诱发了一个更正性的ERP成分（P200-300）,在300～400ms时间段,两种反馈诱发的ERP成分（P300）没有差异,而在450～500ms时间段, “撒谎逃过检测”比“撒谎被抓住”的反馈信息诱发了一个更负性的ERP成分（N500）,负性反馈没有诱发FRN。这些结果表明：P200-300、P300和N500都是与加工测谎结果信息有关的ERP成分。P200-300可能对测谎结果的效价（正性或负性）敏感;P300可能反映被试对测谎结果主观意义大小的评价;而N500可能反映测谎结果所导致的大脑皮层兴奋程度。     

A novel method for assessing rival models of recognition memory

A general comparison is made between the multinomial processing tree (MPT) approach and a strength-based approach for modeling recognition memory measurement. Strength models include the signal-detection model and the dual-process model. Existing MPT models for recognition memory and a new generic MPT model, called the Multistate (MS) model, are contrasted with the strength models. Although the ROC curves for the MS model and strength model are similar, there is a critical difference between existing strength models and MPT models that goes beyond the assessment of the ROC. This difference concerns the question of stochastic mixtures for foil test trials. The hazard function and the reverse hazard function are powerful methods for detecting the presence of a probabilistic mixture. Several new theorems establish a novel method for obtaining information about the hazard function and reverse hazard function for the latent continuous distributions that are assumed in the strength approach to recognition memory. Evidence is provided that foil test trials involve a stochastic mixture. This finding occurred for both short-term memory procedures, such as the Brown–Peterson task, and long-term list-learning procedures, such as the paired-associate task. The effect of mixtures on foil trials is problematic for existing strength models but can be readily handled by MPT models such as the MS model. Other phenomena, such as the mirror effect and the effect of target-foil similarity, are also predicted accurately by the MPT modeling framework.     

Signal detection models for the same–different task

Signal detection models for the same–different task are presented. In contrast to the standard approach that only considers the proportion correct, the models apply to the full four by two same–different table. The approach allows one to consider models that recognize bias and other effects. Two basic signal detection models, associated with different decision rules, are presented. A version of the covert decisions rule is introduced that directly allows for same–different bias, in contrast to earlier versions. It is shown how to fit the models with standard software for nonlinear mixed models. The models are applied to data from a recent same–different study.