Visual hemispatial neglect, re-assessed

Abstract

Increased computer use in clinical settings offers an opportunity to develop new neuropsychological tests that exploit the control computers have over stimulus dimensions and timing. However, before adopting new tools, empirical validation is necessary. In the current study, our aims were twofold: to describe a computerized adaptive procedure with broad potential for neuropsychological investigations, and to demonstrate its implementation in testing for visual hemispatial neglect. Visual search results from adaptive psychophysical procedures are reported from 12 healthy individuals and 23 individuals with unilateral brain injury. Healthy individuals reveal spatially symmetric performance on adaptive search measures. In patients, psychophysical outcomes (as well as those from standard paper-and-pencil search tasks) reveal visual hemispatial neglect. Consistent with previous empirical studies of hemispatial neglect, lateralized impairments in adaptive conjunction search are greater than in adaptive feature search tasks. Furthermore, those with right hemisphere damage show greater lateralized deficits in conjunction search than do those with left hemisphere damage. We argue that adaptive tests, which automatically adjust to each individual's performance level, are efficient methods for both clinical evaluations and neuropsychological investigations and have the potential to detect subtle deficits even in chronic stages, when flagrant clinical signs have frequently resolved. (JINS, 2008, 14, 243-256.)

Global statistical regularities modulate the speed of visual search in patients with focal attentional deficits

“…It has been repeatedly demonstrated that patients with minimal evidence of neglect on traditional measures (like typical cancelation and line bisection tasks used to assess patients in the present investigation) nonetheless exhibit notable impairments in more precisely controlled adaptive computerized tasks, such as conjunctive search (e.g., List et al, 2008) and dual-task paradigms (e.g., Bonato et al, 2013) simulating attentional demands more similar to those of real-world interactions. Furthermore, as previously noted, visual neglect also involves a fundamental loss of attentional capacity throughout the visual field (for reviews, see Robertson, 2001; Husain and Rorden, 2003).…”

The single interval adjustment matrix (SIAM) yes–no task: an empirical assessment using auditory and gustatory stimuli

“…The 2AFC procedure is generally considered to be less affected by bias than the yes-no task and provides relatively simple data for analysis, though it is made less efficient by the requirement for two observation intervals, as opposed to one. Several researchers have used the SIAM YN task in areas such as visual feature search with hemineglect patients (Brooks, Wong, & Robertson, 2005;List et al, 2008), brightness matching (Brown & Rudd, 1998), and auditory filter measurements (Leeuw & Dreschler, 1998). However, 20 years have passed since the description of the SIAM YN task was published (i.e., since Kaernbach, 1990b), and these studies appear to be the only reported use of the SIAM task.…”

Sustained attention training reduces spatial bias in Parkinson’s disease: a pilot case series

“…The conjunction search requires observers to search for a target object (e.g., red square) among a display of 13 or 14 distractors that are either the same color or the same shape as the target object (e.g., red triangles and blue squares, see List et al, 2008 for a more complete description). The participants were instructed to look at the fixation cross in the center of the screen at the beginning of each trial, and then to verbally indicate whether the target was present or not by verbalizing “yes” or “no”.…”

“…The initial display duration was set at 2000 ms and we manipulated the display duration to reach an adjusted accuracy rate of 75% (further details of this procedure are provided in List et al, 2008). Staircases terminated after 10 reversals (when the answer from one trial to the next went from correct to incorrect or vice versa).…”