Knowledge that Transforms

A hallmark of both visual attention and working memory is their severe capacity limit: People can attentively track only about four objects in a multiple object tracking (MOT) task and can hold only up to four objects in visual working memory (VWM). It has been proposed that attention underlies the capacity limit of VWM. We tested this hypothesis by determining the effect of varying the load of a MOT task performed during the retention interval of a VWM task and comparing the resulting dual-task costs with those observed when a VWM task was performed concurrently with another VWM task or with a verbal working memory task. Instead of supporting the view that the capacity limit of VWM is solely attention based, the results indicate that VWM capacity is set by the interaction of visuospatial attentional, central amodal, and local task-specific sources of processing.

Two years ago, a widely circulated statement on the Internet claimed that resarceh at Cmabrigde Uinervtisy fuond that sentecnes in whcih lettres weer transpsoed (or jubmled up), as in the setnence you are now raeding, were easy to read and that letter position in words was not important to the ability to read successfully. In actuality, the statement was a hoax in that no such research had been conducted at the University of Cambridge (see http://www.mrc-cbu.cam.ac.uk/personal/matt.davis/Cmabrigde/). We report here results from a study showing that although some variations of sentences with transposed letters are relatively easy to read, other variations are not, and that there is generally always a cost associated with reading words with transposed letters.

Aggression-related cues (e.g., violent media) can prime both hostile thoughts and the tendency to commit aggression. However, not everyone engages in an aggressive act after being exposed to an aggression-related cue. Some thought pattern, perhaps an automatic one, may prevent the cue-aggression sequence in some individuals. These considerations motivated the present research, which examined the potential for agreeableness to moderate the effect of aggression-related cues on behavior and cognition. In Study 1, we found that priming with aggression-related cues increased aggressive behavior, but only among individuals low in agreeableness. Study 2 showed that aggression-related cues activated prosocial thoughts among individuals high in agreeable affect (a component of agreeableness). These results reveal that agreeable individuals are able to short-circuit the cue-aggression sequence, likely by recruiting prosocial thoughts in response to aggression-related primes.

The present study used event-related potentials (ERPs) to examine the time course of orthographic and phonological priming in the masked priming paradigm. Participants monitored visual target words for occasional animal names, and ERPs to nonanimal critical items were recorded. These critical items were preceded by different types of primes: Orthographic priming was examined using transposed-letter (TL) primes (e.g., barin-BRAIN) and their controls (e.g., bosin-BRAIN); phonological priming was examined using pseudohomophone primes (e.g., brane-BRAIN) and their controls (e.g., brant-BRAIN). Both manipulations modulated the N250 ERP component, which is hypothesized to reflect sublexical processing during visual word recognition. Orthographic (TL) priming and phonological (pseudohomophone) priming were found to have distinct topographical distributions and different timing, with orthographic effects arising earlier than phonological effects.

The fluency of cognitive processes influences many judgments: Fluently processed statements are judged to be true, fluently processed instances are judged to be frequent, and fluently processed names are judged to be famous. According to a cue-learning approach, these effects of experienced fluency arise because the fluency cue is interpreted differentially in accordance with its learned validity. Two experiments tested this account by manipulating the fluency cue's validity. Fluency was manipulated by color contrast (Experiment 1) and by required mental rotation (Experiment 2). If low fluency was correlated with a required affirmative or "old" response (and high fluency with a negative or "new" response) in a training phase, participants showed a reversal of the classic pattern in the recognition phase: Low-fluency stimuli had a higher probability than high-fluency stimuli to be classified as old. Thus, the interpretation and therefore the impact of fluency depended on the cue's learned validity.

Because different processes underlie implicit and explicit attitudes, we hypothesized that they are differentially sensitive to different kinds of information. We measured implicit and explicit attitudes over time, as different types of attitude-relevant information about a single attitude object were presented. As expected, explicit attitudes formed and changed in response to the valence of consciously accessible, verbally presented behavioral information about the target. In contrast, implicit attitudes formed and changed in response to the valence of subliminally presented primes, reflecting the progressive accretion of attitude object-evaluation pairings. As a consequence, when subliminal primes and behavioral information were of opposite valence, people formed implicit and explicit attitudes of conflicting valence.

We sought to extend earlier work by examining whether there are ordinary variations in human maternal caregiving behavior (MCB) that are related to stress reactivity in infants. We observed 185 mother-infant dyads and used standard coding systems to identify variations in caregiving behavior. We then created two extreme groups and found that infants receiving low-quality MCB showed more fearfulness, less positive joint attention, and greater right frontal electroencephalographic asymmetry than infants receiving high-quality MCB. Group differences in stress reactivity were not a result of measured infant temperament. However, infants receiving low-quality MCB manifested significantly more negative affect during caregiving activities than did infants receiving high-quality MCB. The results suggest that ordinary variations in MCB may influence the expression of neural systems involved in stress reactivity in human infants.

Glucocorticoid hormones have been shown to enhance memory consolidation when applied at low doses posttraining, but are ineffective or impair memory at high doses. In a test of whether this quadratic relationship also exists for endogenously released glucocorticoids, healthy men and women received cold-pressor stress (CPS) or a control procedure immediately after reading a relatively neutral story and were tested for retention 1 week later. Cortisol levels in response to the stressor were assayed from saliva. CPS significantly elevated salivary cortisol in both sexes, but enhanced memory only in male subjects. Among CPS-treated male subjects, there was a significant quadratic correlation between cortisol release posttraining and subsequent memory. Thus, these findings represent the first demonstration of an inverted-U relationship between activity of endogenous stress hormones and human memory.

Monitoring of ongoing processing plays a critical role in regulating cognitive function. Two event-related potential components, the error-related negativity (ERN) and N2, have been proposed to reflect this monitoring function. Specifically, it has been suggested that both components reflect the role of anterior cingulate cortex (ACC) in monitoring for the occurrence of response conflict. This view appears to be challenged by findings that alcohol consumption and lesions in ACC have dissociable effects on the ERN and N2. Using a computational model, the present research demonstrates that the conflict-monitoring theory can account for these dissociations in terms of the dissociable effects of alcohol and ACC lesions on processing of relevant stimulus information (which determines ERN amplitude) and processing of irrelevant, distracting information (which determines N2 amplitude). The simulation results suggest new interpretations of the cognitive deficits caused by alcohol consumption (impaired stimulus processing) and ACC lesions (impaired attentional control).

When learners encode sequential patterns and generalize their knowledge to novel instances, are they relying on abstract or stimulus-specific representations? Research on artificial grammar learning (AGL) has shown transfer of learning from one stimulus set to another, and such findings have encouraged the view that statistical learning is mediated by abstract representations that are independent of the sense modality or perceptual features of the stimuli. Using a novel modification of the standard AGL paradigm, we obtained data to the contrary. These experiments pitted abstract processing against stimulus-specific learning. The findings show that statistical learning results in knowledge that is stimulus-specific rather than abstract. They show furthermore that learning can proceed in parallel for multiple input streams along separate perceptual dimensions or sense modalities. We conclude that learning sequential structure and generalizing to novel stimuli inherently involve learning mechanisms that are closely tied to the perceptual characteristics of the input.