Scott Watter

The n-back as a dual-task: P300 morphology under divided attention.

The n-back task was hypothesized to be a dual task, permitting the imposition of parametrically increasing attentional and working memory demands, while keeping constant the demands of an embedded matching subtask. Visual targets were presented for 200 ms every 2.2 s at pseudorandomly varying positions on a computer screen. Participants were required to remember the most recent 0, 1, 2, or 3 positions and responded with a choice button push to whether the current target position matched the position presented n items previously. P300 peak latency was constant across n-back tasks, reflecting constant perceptual and cognitive demands of the matching subtask. P300 peak amplitude decreased with increasing memory load, reflecting reallocation of attention and processing capacity away from the matching subtask to working memory activity. These data support a dual-task nature of the n-back, which should be considered when employing this paradigm.

Task switching in video game players: Benefits of selective attention but not resistance to proactive interference

Research into the perceptual and cognitive effects of playing video games is an area of increasing interest for many investigators. Over the past decade, expert video game players (VGPs) have been shown to display superior performance compared to non-video game players (nVGPs) on a range of visuospatial and attentional tasks. A benefit of video game expertise has recently been shown for task switching, suggesting that VGPs also have superior cognitive control abilities compared to nVGPs. In two experiments, we examined which aspects of task switching performance this VGP benefit may be localized to. With minimal trial-to-trial interference from minimally overlapping task set rules, VGPs demonstrated a task switching benefit compared to nVGPs. However, this benefit disappeared when proactive interference between tasks was increased, with substantial stimulus and response overlap in task set rules. We suggest that VGPs have no generalized benefit in task switching-related cognitive control processes compared to nVGPs, with switch cost reductions due instead to a specific benefit in controlling selective attention.

Automatic face identity encoding at the N170

The N170 event-related potential component is currently under investigation for its role in face identity processing. Using a location-matching paradigm, in which face identity is task irrelevant, we observed a progressive decrease in N170 amplitude to multiple repetitions of upright faces presented at unattended locations. In contrast, we did not observe N170 habituation for repeat presentations of inverted faces. The findings suggest that the N170 repetition effects reflect early face identity processes that are part of familiarity acquisition of new faces.

Progressive N170 habituation to unattended repeated faces

This study utilized a location-matching task to investigate whether the face-sensitive N170 event-related potential component would habituate in its response to the repeated presentation of same face stimuli when face identity was irrelevant to the experimental task. N170 amplitude decreased progressively with repeated presentation of the same face vs. sequential presentation of novel faces. This N170 habituation to face identity repetition occurred only for faces at unattended spatial locations, likely representing a relatively pure observation of automatic early face processing.

Leximancer concept mapping of patient case studies

Quantitative databases are limited to information identified as important by their creators, while databases containing natural language are limited by our ability to analyze large unstructured bodies of text. Leximancer is a tool that uses semantic mapping to develop concept maps from natural language. We have applied Leximancer to educational based pathology case notes to demonstrate how real patient records or databases of case studies could be analyzed to identify unique relationships. We then discuss how such analysis could be used to conduct quantitative analysis from databases such as the Coronary Heart Disease Database.

Parallel response selection in dual-task situations

Semantic priming and response priming were studied in a dual-task procedure. In two experiments, reaction times to the first and second stimuli were faster when the finger required for the Task 1 response was the same as the finger required for the Task 2 response. Such priming suggests that Task 2 response information was generated prior to the completion of Task 1 response selection. These data pose a potential challenge to the response-selection bottleneck (RSB) theory of dual-task performance, since they may indicate a violation of the discrete-stage processing assumption on which the underlying locus-of-slack logic depends. Accommodating these data while preserving the essential bottleneck character of RSB theory may be possible but may also alter the very nature of the bottleneck itself.

Control processes in verbal working memory: An event-related potential study

Event-related potentials (ERPs) were recorded using a large electrode array while subjects engaged in tasks designed to dissociate control from storage/maintenance processes in verbal working memory (WM). Increased ERP negativity (450-900 ms post-stimulus onset) over left frontal regions emerged only when required dynamic updating/revision of WM stores was initiated, with augmentation of right frontal negativity in the same epoch relative to more general overall task demands. Increased ERP positivity in a similar time window over parietal regions reflected initiation of required rehearsal/maintenance of memory set contents, with progressive amplitude increases with repeated dynamic updating/revision of memory stores, suggesting increased effortful activity to resist proactive interference effects. These findings are consistent with a left frontal-parietal network for process control in verbal working memory.

Being a grump only makes things worse: a transactional account of acute stress on mind wandering

The current work investigates the influence of acute stress on mind wandering. Participants completed the Positive and Negative Affect Schedule as a measure of baseline negative mood, and were randomly assigned to either the high-stress or low-stress version of the Trier Social Stress Test. Participants then completed the Sustained Attention to Response Task as a measure of mind-wandering behavior. In Experiment 1, participants reporting a high degree of negative mood that were exposed to the high-stress condition were more likely to engage in a variable response time, make more errors, and were more likely to report thinking about the stressor relative to participants that report a low level of negative mood. These effects diminished throughout task performance, suggesting that acute stress induces a temporary mind-wandering state in participants with a negative mood. The temporary affect-dependent deficits observed in Experiment 1 were replicated in Experiment 2, with the high negative mood participants demonstrating limited resource availability (indicated by pupil diameter) immediately following stress induction. These experiments provide novel evidence to suggest that acute psychosocial stress briefly suppresses the availability of cognitive resources and promotes an internally oriented focus of attention in participants with a negative mood.

Priming honesty reduces subjective bias in self-report measures of mind wandering

Using self-report as a measure of conscious experience has been a point of contention in mind wandering research. Whereas prior work has focused on the introspective component of self-report validity, the current research introduces an honesty prime task to the current paradigm in order to assess the role of goal states and social factors on self-report accuracy. Findings provide evidence for an inflated report of mind wandering frequency arising from demand characteristics, intensified by the divergent properties of the subjective and behavioural measures and the general deficit in meta-awareness of off task episodes.

Phonological facilitation from pictures in a word association task: evidence for routine cascaded processing in spoken word production.

While most authors now agree that the language production system is in principle cascaded, the strength with which cascaded lemma-to-phoneme activation typically occurs is debated. Picture naming has been shown to be facilitated by phonologically related distractor pictures, but no such facilitation from pictures has been shown for word reading. Picture–picture paradigms have recently been suggested to represent an attentionally facilitated and unusually strong case of cascaded phonological facilitation, not typical of a more general weakly cascaded production system. We used a novel procedure based on picture–word interference paradigms, where participants made speeded verbal free association responses to presented words, with irrelevant picture distractors that were phonologically related to their predicted high-associate responses. Phonological facilitation effects from related picture names were observed on free associate verbal production latencies. These findings represent a far more general demonstration of routine cascaded language production and suggest that the strength and extent of cascaded activation is more substantial than that suggested by traditional picture–word paradigms.