Signal Detection Models with Random Participant and Item Effects

The theory of signal detection is convenient for measuring mnemonic ability in recognition memory paradigms. In these paradigms, randomly selected participants are asked to study randomly selected items. In practice, researchers aggregate data across items or participants or both. The signal detection model is nonlinear; consequently, analysis with aggregated data is not consistent. In fact, mnemonic ability is underestimated, even in the large-sample limit. We present two hierarchical Bayesian models that simultaneously account for participant and item variability. We show how these models provide for accurate estimation of participants’ mnemonic ability as well as the memorability of items. The model is benchmarked with a simulation study and applied to a novel data set. This research is supported by NSF grants SES-0095919 and SES-0351523, NIH grant R01-MH071418, a University of Missouri Research Leave grant and fellowships from the Spanish Ministry of Education and the University of Leuven, Belgium.     

Attentive processing of threat and adult attachment: a dot-probe study

We examined selective attention to threat stimuli as a function of individual differences in adult attachment. Participants completed a dot-probe task in which a general threat word, attachment-related threat word, general positive or attachment-related positive word was presented together with a neutral word. Results showed that attachment anxiety and avoidance were associated with an attentional bias away from attachment threat words. This attentional avoidance effect was best predicted by the interaction between attachment anxiety and avoidance and not by their unique main effects. The findings are discussed in terms of attachment theory and its relation to attentional biases observed in psychopathology.     

The effect of visual threat on spatial attention to touch

Viewing a threatening stimulus can bias visual attention toward that location. Such effects have typically been investigated only in the visual modality, despite the fact that many threatening stimuli are most dangerous when close to or in contact with the body. Recent multisensory research indicates that a neutral visual stimulus, such as a light flash, can lead to a tactile attention shift towards a nearby body part. Here, we investigated whether the threat value of a visual stimulus modulates its effect on attention to touch. Participants made speeded discrimination responses about tactile stimuli presented to one or other hand, preceded by a picture cue (snake, spider, flower or mushroom) presented close to the same or the opposite hand. Pictures of snakes led to a significantly greater tactile attentional facilitation effect than did non-threatening pictures of flowers and mushrooms. Furthermore, there was a correlation between self-reported fear of snakes and spiders and the magnitude of early facilitation following cues of that type. These findings demonstrate that the attentional bias towards threat extends to the tactile modality and indicate that perceived threat value can modulate the cross-modal effect that a visual cue has on attention to touch.     

Victim’s innocence, social categorization, and the threat to the belief in a just world

This research studies people’s reactions to the suffering of victims, examining the hypothesis of the belief in a just world (BJW) (Lerner, 1980) according to which the awareness of innocent victims threatens people’s BJW, and extending the scope of BJW theory to intergroup contexts. An implicit measure of the threat to the BJW (Hafer, 2000a) is used in this research. After participants viewed a videotaped film containing the victimization story they performed an emotional modified Stroop task. Study 1 examined the threat to the BJW as function of the innocence of the victim at an interpersonal level of analysis. Results show that only the innocent victim threatens the observer’s BJW. Study 2 examined the threat to the BJW as function of the victim’s group and of the victim’s innocence. Results show that an ingroup victim threatens the participant’s BJW more than a victim belonging to an outgroup.     

Can mismatch negativity be linked to synaptic processes? A glutamatergic approach to deviance detection

This article aims to provide a theoretical framework to elucidate the neurophysiological underpinnings of deviance detection as reflected by mismatch negativity. A six-step model of the information processing necessary for deviance detection is proposed. In this model, predictive coding of learned regularities is realized by means of long-term potentiation with a crucial role for NMDA receptors. Mismatch negativity occurs at the last stage of the model, reflecting the increase in free energy associated with the switching on of silent synapses and the formation of new neural circuits required for adaptation to the environmental deviance. The model is discussed with regard to the pathological states most studied in relation to mismatch negativity: alcohol intoxication, alcohol withdrawal, and schizophrenia.     

中医望诊中眼神跟踪与分析综述

望诊是中医四诊中的一种,也是中医查病的第一步。而眼睛是心灵的窗户,医师通过望眼神能够诊测一个人的身体健康状况,眼睛与身体的对应有众多说法,如"五轮八廓"等,因此眼神的跟踪与分析对于中医望诊十分重要。使用电脑对眼神的进行自动跟踪首先需要进行眼睛各部位的精确定位,包括眼皮、眼角、白睛、眼结膜、虹膜、瞳孔以及眼袋等;接着需要对眼睛的动作进行跟踪,包括眼球的转动、瞳孔的放缩等。对眼神的分析在定位与跟踪之后,由眼球各部分的形状、颜色、移动速度等信息结合相应的规则对病位、病性作出判断。本文综述了中医中望眼的一些经验总结,并给出了目前用于眼睛定位、跟踪的算法与思路。     

Constructing a desert labyrinth: The psychological and emotional geographies of deterrence strategy on the U.S. / Mexico border

Confinement, hindrance, and time bring anxiety, fear, and stress, often accompanied by confusion and desperation. In the case of undocumented immigrants in the Sonoran Desert, such conditions are manipulated by way of surveillance and policing. These conditions, in combination with physical exertion, augment a physiological stress response that coalesces with existing traumas and fear. We undertake a critical mapping of relations among enforcement infrastructure, migration routes, and measurable features of the physical landscape to demonstrate that a corridor in the region functions as a labyrinth, an outcome of a combination of threats and stressors determined by the spaces migrants find themselves in after crossing the U.S./Mexico border. We argue a biopolitical understanding of current border policies indicates it reduces migrants to bare life rather than using threat, stressors, or trauma as instruments for manipulating behavior. We discuss how this labyrinth works in combination with other mechanisms, including criminalization, detention, abuse, separation, and deportation, to deliver consequences that may deter migration. Despite these efforts, migration routes remain plastic, indicating the continued potential to resist and evade the surveillance technologies and enforcement deployed in the borderlands. We assert that an inevitable result of the desert labyrinth is human mortality.     

Traditional difference-score analyses of reasoning are flawed

Studies of the belief bias effect in syllogistic reasoning have relied on three traditional difference score measures: the logic index, belief index, and interaction index. Dube, Rotello, and Heit (2010, 2011) argued that the interaction index incorrectly assumes a linear receiver operating characteristic (ROC). Here, all three measures are addressed. Simulations indicated that traditional analyses of reasoning experiments are likely to lead to incorrect conclusions. Two new experiments examined the role of instructional manipulations on the belief bias effect. The form of the ROCs violated assumptions of traditional measures. In comparison, signal detection theory (SDT) model-based analyses were a better match for the form of the ROCs, and implied that belief bias and instructional manipulations are predominantly response bias effects. Finally, reanalyses of previous studies of conditional reasoning also showed non-linear ROCs, violating assumptions of traditional analyses. Overall, reasoning research using traditional measures is at risk of drawing incorrect conclusions.     

Frontal and parietal EEG asymmetries interact to predict attentional bias to threat

Frontal and parietal electroencephalographic (EEG) asymmetries mark vulnerability to depression and anxiety. Drawing on cognitive theories of vulnerability, we hypothesise that cortical asymmetries predict attention to threat. Participants completed a dot-probe task in which bilateral face displays were followed by lateralised targets at either short (300 ms) or long (1050 ms) SOA. We also measured N2pc to face onset as an index of early attentional capture. At long SOA only, frontal and parietal asymmetry interacted to predict attentional bias to angry faces. Those with leftward frontal asymmetry showed no attentional bias. Among those with rightward frontal asymmetry those with low right parietal activity showed vigilance for threat, and those with high right parietal activity showed avoidance. Asymmetry was not related to the N2pc or to attentional bias at the short SOA. Findings suggest that trait asymmetries reflect function in a fronto-parietal network that controls attention to threat.     

Blur detection is unaffected by cognitive load

Blur detection is affected by retinal eccentricity, but is it also affected by attentional resources? Research showing effects of selective attention on acuity and contrast sensitivity suggests that allocating attention should increase blur detection. However, research showing that blur affects selection of saccade targets suggests that blur detection may be pre-attentive. To investigate this question, we carried out experiments in which viewers detected blur in real-world scenes under varying levels of cognitive load manipulated by the N-back task. We used adaptive threshold estimation to measure blur detection thresholds at 0°, 3°, 6°, and 9° eccentricity. Participants carried out blur detection as a single task, a single task with to-be-ignored letters, or an N-back task with four levels of cognitive load (0, 1, 2, or 3-back). In Experiment 1, blur was presented gaze-contingently for occasional single eye fixations while participants viewed scenes in preparation for an easy picture recognition memory task, and the N-back stimuli were presented auditorily. The results for three participants showed a large effect of retinal eccentricity on blur thresholds, significant effects of N-back level on N-back performance, scene recognition memory, and gaze dispersion, but no effect of N-back level on blur thresholds. In Experiment 2, we replicated Experiment 1 but presented the images tachistoscopically for 200 ms (half with, half without blur), to determine whether gaze-contingent blur presentation in Experiment 1 had produced attentional capture by blur onset during a fixation, thus eliminating any effect of cognitive load on blur detection. The results with three new participants replicated those of Experiment 1, indicating that the use of gaze-contingent blur presentation could not explain the lack of effect of cognitive load on blur detection. Thus, apparently blur detection in real-world scene images is unaffected by attentional resources, as manipulated by the cognitive load produced by the N-back task.