Read-out of emotional information from iconic memory: the longevity of threatening stimuli

Previous research has shown that emotional stimuli are more likely than neutral stimuli to be selected by attention, indicating that the processing of emotional information is prioritized. In this study, we examined whether the emotional significance of stimuli influences visual processing already at the level of transient storage of incoming information in iconic memory, before attentional selection takes place. We used a typical iconic memory task in which the delay of a poststimulus cue, indicating which of several visual stimuli has to be reported, was varied. Performance decreased rapidly with increasing cue delay, reflecting the fast decay of information stored in iconic memory. However, although neutral stimulus information and emotional stimulus information were initially equally likely to enter iconic memory, the subsequent decay of the initially stored information was slowed for threatening stimuli, a result indicating that fear-relevant information has prolonged availability for read-out from iconic memory. This finding provides the first evidence that emotional significance already facilitates stimulus processing at the stage of iconic memory.     

Relative visual saliency differences induce sizable bias in consumer choice

Consumers often need to make very rapid choices among multiple brands (e.g., at a supermarket shelf) that differ both in their reward value (e.g., taste) and in their visual properties (e.g., color and brightness of the packaging). Since the visual properties of stimuli are known to influence visual attention, and attention is known to influence choices, this gives rise to a potential visual saliency bias in choices. We utilize experimental design from visual neuroscience in three real food choice experiments to measure the size of the visual saliency bias and how it changes with decision speed and cognitive load. Our results show that at rapid decision speeds visual saliency influences choices more than preferences do, that the bias increases with cognitive load, and that it is particularly strong when individuals do not have strong preferences among the options.     

Attention and consciousness: two distinct brain processes

The close relationship between attention and consciousness has led many scholars to conflate these processes. This article summarizes psychophysical evidence, arguing that top-down attention and consciousness are distinct phenomena that need not occur together and that can be manipulated using distinct paradigms. Subjects can become conscious of an isolated object or the gist of a scene despite the near absence of top-down attention; conversely, subjects can attend to perceptually invisible objects. Furthermore, top-down attention and consciousness can have opposing effects. Such dissociations are easier to understand when the different functions of these two processes are considered. Untangling their tight relationship is necessary for the scientific elucidation of consciousness and its material substrate.     

The Graded Response Differential Discrimination Model Accounting for Extreme Response Style

Extreme response style or, more generally, individual differences in response spacing have been shown to be an influential bias when analyzing questionnaire data. Recently a promising model adjusting for this bias — the differential discrimination model — has been proposed. An advantage to other related approaches is that the model can be fitted using standard structural equation modeling software. However, the model is designed for analyzing continuous item responses, whereas graded response formats are certainly more prominent in behavioral sciences. To resolve this limitation, the present article extends the differential discrimination model to analyzing graded responses. Empirical examples as well as a small simulation study are presented.     

Eye movements in a simple spatial reasoning task

We report two experiments in which participants read a question about the spatial relationship between two letters, then viewed a visual display containing the letters and were required to respond to the question. The format of the question influenced the nature of the eye movements generated to the visual display. Participants also had a tendency to make additional eye movements in order to generate a fixation sequence that corresponded to the order of the letters in the question. This demonstrates an influence of stored information on eye movement generation, and suggests that the scanpath plays a role in structuring the visual information to facilitate reasoning.     

Motion-induced blindness does not affect the formation of negative afterimages

Aftereffects induced by invisible stimuli constitute a powerful tool to investigate what type of neural information processing can occur in the absence of visual awareness. This approach has been successfully used to demonstrate that awareness of oriented gratings or translating stimuli is not necessary to obtain a robust orientation-specific or motion-specific aftereffect. We exploit motion-induced blindness (MIB, Bonneh, Cooperman, & Sagi, 2001) to investigate the related question of the influence of visual awareness on the formation of negative afterimages. Our results show that MIB does not affect the persistence and intensity of afterimages. Thus, there is no significant contribution to the formation of afterimages beyond the sites mediating MIB.     

Indexing systematic rater agreement with a latent-class model

A latent-class model of rater agreement is presented for which 1 of the model parameters can be interpreted as the proportion of systematic agreement. The latent classes of the model emerge from the factorial combination of the "true" category in which a target belongs and the ease with which raters are able to classify targets into the true category. Several constrained cases of the model are described, and the relations to other well-known agreement models and kappa-type summary coefficients are explained. The differential quality of the rating categories can be assessed on the basis of the model fit. The model is illustrated using data from diagnoses of psychiatric disorders and classifications of individuals in a persuasive communication study.     

Eye movements reflect and shape strategies in fraction comparison

The comparison of fractions is a difficult task that can often be facilitated by separately comparing components (numerators and denominators) of the fractions—that is, by applying so-called component-based strategies. The usefulness of such strategies depends on the type of fraction pair to be compared. We investigated the temporal organization and the flexibility of strategy deployment in fraction comparison by evaluating sequences of eye movements in 20 young adults. We found that component-based strategies could account for the response times and the overall number of fixations observed for the different fraction pairs. The analysis of eye movement sequences showed that the initial eye movements in a trial were characterized by stereotypical scanning patterns indicative of an exploratory phase that served to establish the kind of fraction pair presented. Eye movements that followed this phase adapted to the particular type of fraction pair and indicated the deployment of specific comparison strategies. These results demonstrate that participants employ eye movements systematically to support strategy use in fraction comparison. Participants showed a remarkable flexibility to adapt to the most efficient strategy on a trial-by-trial basis. Our results confirm the value of eye movement measurements in the exploration of strategic adaptation in complex tasks.     

Consistent Differential Discrimination Model Estimation

A novel factor-analytic model—the differential discrimination model—for assessing individual differences in scale use has been recently introduced, together with a three-stage estimation approach for model fitting. Unfortunately, the second-stage estimator and, as a consequence, the third-stage estimator of this procedure are not consistent. In this article we show that (a) the differential discrimination model can be expressed in a structural equation model framework, and (b) consistent and simultaneous estimation of all model parameters can be achieved using standard SEM software.     

A note on residual M-distances for identifying aberrant response patterns

Although a statistical model might fit well to a large proportion of the individuals of a random sample, some individuals might give ‘unusual’ responses that are not well explained by the hypothesized model. If individual responses are given as continuous response vectors, M-distances can be used to produce real valued indicators of how well an individual's response vector corresponds to a covariance structure implied by a psychometric model. In this note, we focus on the so-called one-factor model. Two M-distances, d_si and d_ri, which are sensitive to different aspects of the assumed factor model, have been proposed. While one of the M-distances, d_ri, has been derived based on Bartlett factor scores, in this note we show that the second M-distance, d_si, can be derived in an analogous fashion based on Thomson factor scores.