Divided attention for feature-based selection in visual cortex

Feature-based attention can select relevant features such as colors or directions of motion from the visual field irrespective of the spatial position. In visual cortex not only do we see feature-specific attention affecting responses in neurons with receptive fields at an attended location, but that effect also spreads to neurons with receptive fields beyond the spatially relevant location. When only one feature is task relevant, the spread of activity across space can act to facilitate perception of behaviorally relevant stimuli. However, when multiple features are relevant, what is the effect on behavior and brain activity? We tested this question by having observers divide attention between two patches (left and right of fixation) of moving dot stimuli, each containing overlapping upward and downward motion fields. In one condition, subjects performed a task on motion fields moving in the same direction in both patches. In another condition attention was divided between opposite directions of motion. Replicating a previous behavioral study, we found that observers showed better performance when dividing attention to the same directions of motion than opposing directions of motion. We analyzed the BOLD responses while observers performed this task using an inverted encoding model approach that provides estimates of responses to each of the four component dot fields. We found larger responses to the attended components, replicating previous studies of spatial and feature-based attention. However, these effects were much larger when attention was divided to between the same directions of motion than to opposing directions. Our fMRI results in area hMT+ predict our behavioral results by extending the normalization model of attention to include a global feature-based attention component in that leads to suppressed responses to attended stimulus components when attention is directed to opposing directions of motion.

Does action disrupt Multiple Object Tracking (MOT)?

While the relationship between action and focused attention has been well-studied, less is known about the ability to divide attention while acting. In the current paper we explore this issue using the multiple object tracking (MOT) paradigm (Pylyshyn & Storm, 1988). We asked whether planning and executing a display-relevant action during tracking would substantially affect the ability track and later identify targets. In all trials the primary task was to track 4 targets among a set of 8 identical objects. Several times during each trial, one object, selected at random, briefly changed colour. In the baseline MOT trials, these changes were ignored. During active trials, each changed object had to be quickly touched. On a given trial, changed objects were either from the tracking set or were selected at random from all 8 objects. Although there was a small dual-task cost, the need to act did not substantially impair tracking under either touch condition.

The Role of the Dorsolateral Prefrontal Cortex in Bimodal Divided Attention: Two Transcranial Magnetic Stimulation Studies

The neural processes underlying the ability to divide attention between multiple sensory modalities remain poorly understood. To investigate the role of the dorsolateral prefrontal cortex (DLPFC) in bimodal divided attention, we completed two repetitive transcranial magnetic stimulation (rTMS) studies. We tested the hypothesis that the DLPFC is necessary in the ability to divide attention across modalities. This hypothesis originated as a result of a previous fMRI study in which the posterior DLPFC was active during a bimodal divided attention condition [Johnson, J. A., & Zatorre, R. J. Neural substrates for dividing and focusing attention between simultaneous auditory and visual events. Neuroimage, 2006]. In the current experiments, two separate groups of subjects underwent 10 min of slow rTMS to temporarily disrupt function of the DLPFC. In both groups, the ability to divide attention between unrelated auditory and visual stimuli decreased following DLPFC disruption compared to control site stimulation. Specifically, the ability to divide attention between modalities was hindered, leading to a pattern of behavior similar to bimodal selective attention (ability to attend to one or the other modality but not both). We discuss possible roles of the posterior DLPFC in bimodal divided attention and conclude that the area may be functioning to support the increased working memory load associated with divided, compared to selective attention.

Rethinking the Design of Presentation Slides: Creating Slides That Are Readily Comprehended

Presentation slides, when designed well, can significantly increase the amount of information that the audience comprehends. However, when the slide has type that can not be quickly read, the audience often gives up on the slide. Moreover, when the slide does not orient well, when the slide has too much information, or when the order of information on the slide is unclear, the audience can easily become confused. Given that these mistakes can prevent the audience from comprehending the presentation’s content, presenters should strive to format slides that can be quickly read, that effectively orient, that have a reasonable amount of information, and that have a clear order of information. Unfortunately, the slide formats that many engineering presenters use do not meet these goals. Presented in this paper are recommendations for the format of presentation slides—specifically, the typography, color, and layout of presentation slides (or overheads). An assumption for these recommendations is that the purpose of the presentation is to communicate technical information efficiently to the audience. Given that assumption, the goal of a slide’s typography is to have type that can be read as quickly as possible. To obtain that goal, this paper recommends a bold sans serif typestyle such as Arial that is at least 18 points. In regard to color, the most important goal is to have colors that can be clearly distinguished from each other. To obtain that goal, this paper recommends either a dark color against a light background or a light color against a dark background. In regard to layout, the goal is to have a slide design for which the audience can quickly discern the point of the slide and then can divide attention between the presenter and the slide as the presenter discusses the slide. To obtain that goal, this paper recommends the national laboratory design of a short sentence headline supported primarily by images. Other reasons exist for choosing this national lab design. Although this paper focuses on how readily that slides following this national lab design can be comprehended, the paper does direct the reader to references that discuss two other reasons for using this national laboratory design: (1) how well the slide design helps the audience remember details, and (2) how persuasive the slide design is.

Splitting the Beam: Distribution of Attention Over Noncontiguous Regions of the Visual Field

In an effort to examine the flexibility with which attention can be allocated in visual space, we investigated whether subjects could selectively attend to multiple noncontiguous locations in the visual field We examined this issue by precuing two separate areas of the visual field and requiring subjects to decide whether the letters that appeared in these locations matched or mismatched while distractors that primed either the match or mismatch response were presented between the cued locations If the distractors had no effect on performance, it would provide evidence that subjects can divide attention over noncontiguous areas of space Subjects were able to ignore the distractors when the targets and distractors were presented as nononset stimuli (i e, when premasks were changed into the targets and distractors) In contrast, when the targets and distractors were presented as sudden-onset stimuli, subjects were unable to ignore the distractors These results begin to define the conditions under which attention can be flexibly deployed to multiple noncontiguous locations in the visual field

Automatic Speech Recognition Applications: A Study of Methods for Defining Command Vocabularies

Phoneme-based automatic speech recognition (ASR) technology enables designers to easily create custom command words or phrases that users can employ to request service operations. In this paper, I report results from two experiments concerning important dimensions of these ASR command vocabularies, including command naturalness/appropriateness and command recallability. Ease of recall is a critical dimension for assessing ASR commands used in multi-step applications since service subscribers may be engaged in several different cognitive activities that divide attention. Yet techniques for measuring command recallability can be difficult to implement owing to the time required for data collection and analysis. Results of these studies indicate the the dimension of command “naturalness” and memorability are closely related: under appropriate conditions, the simple procedures associated with measuring command naturalness or appropriateness can predict retrievability of command expressions.