Guiding Attention in Neurotypical and ADHD Adults: Spatial, Feature, and Temporal Selection History

Abstract

In order to meet the goal of focusing on objects within our visual environment, we must be able to ignore other salient objects that interfere with that goal. We are better able to ignore distracting information when there is a pattern to its presence, such as appearing in a consistent location, color, or at a predictable time. Guiding attention based on our goals is driven by top-down processing, while distraction by salient objects is driven by bottom-up processing. Utilizing learned patterns to guide attention is driven by selection history, in which our past experiences create lingering biases that can influence both the speed of production and the influence of these top-down and bottom-up priority signals. This work aimed to assess the manner in which selection history from different dimensions of distractor regularities influenced bottom-up and top-down priority signals over time to guide attention. Additionally, people with different attentional abilities are likely to have different underlying dynamics of attentional priority. Therefore, this work also aimed to explore the influence of selection history on attentional priority in adults with attention-deficit/hyperactivity disorder (ADHD) compared to neurotypical adults.

Traditional reaction-time measures are unable to interrogate the underlying dynamics of how attentional priority evolves over time. Utilizing a novel experimental method, the “forced-response” method, in conjunction with the additional-singleton task, participants were trained to respond at a fixed time on every trial as indicated by a series of four auditory tones, in which the fourth tone represented the imperative “Go” signal. The critical manipulation was that processing time was systematically varied from trial-to-trial by uniformly presenting the search array at a random time on each trial between 200-1500ms prior to the “Go” signal. An accompanying computational model estimated the latency periods by which competing distractor and target priority signals were produced and their influence over behavior once produced, thus providing an “under the hood” look at the temporal dynamics of attentional priority when distraction competes with a goal.

Spatial distractor regularities enabled participants to proactively suppress the distractor priority signal at the anticipated spatial location while also enhancing target activation and accelerating target processing. Temporal and feature distractor regularities seemed to facilitate behavior through a more reactive mechanism of enhanced target activation in the priority map after stimulus onset. Distractor regularities may guide attentional priority differently for ADHD and NTC participants, though, depending on their baseline attentional control settings. ADHD participants required more baseline processing time to generate target priority signals in an unpredictable Control condition and consequently experienced larger accelerations to their target priority signal latencies than NTC participants did due to the distractor regularities. On the other hand, NTC participants showed lower baseline activation of the target priority signal relative to that of ADHD participants and experienced greater enhancements to target activation than ADHD participants. All in all, the results of this dissertation suggest that the way in which environmental regularities influence attentional priority depends on the dimension of the regularity and that individuals with ADHD do similarly benefit from such regularities, just perhaps through the modulation of different cognitive parameters than neurotypical individuals.