How does the number of targets affect visual search performance in visuospatial neglect?

Abstract

Introduction: Impairments in visual search are a common symptom in visuospatial neglect (VSN). The severity of the lateralized attention bias in visual search tasks can vary depending on the number of distractors: the more distractors, the more targets are missed. However, little is known about how the number of targets affect search performance in VSN. The aim of the current study was to examine the effect of the number of targets on hit rate in VSN. Methods: We included 23 stroke patients with right-brain damage and VSN, 55 with right-brain damage without VSN, and 49 with left-brain damage without VSN, all admitted for inpatient rehabilitation. In a visual search task, patients had to find and tap targets, presented along with non-targets. The location and number of targets varied from trial to trial, allowing the evaluation of the effects of number and location of targets on hit rate. Results: VSN patients detected a lower percentage of targets when more targets were present. For patients with right-brain damage without VSN, adding targets only reduced the hit rate of the most contralesional target. No effect of number of targets on hit rate was seen in patients with left-brain damage. Additionally, VSN patients found less contralesional targets than ipsilesional targets, made more delayed revisits, and had an initial rightward bias when compared to the other groups. There were no differences in search time, search consistency, or immediate revisits between groups. There was a moderate positive relation between the hit rate asymmetry score in our search task and conventional paper-and-pencil VSN tasks, and neglect behavior in daily life. Conclusions: In VSN patients, a higher number of targets reduces the hit rate. The reduced hit rate in visual search evoked by additional targets should be taken into account when assessing visual search in VSN.

Computer-based assessment of unilateral spatial neglect: A systematic review

“…Some studies compared diagnostic accuracy between CB tests, and as expected the more complex CB tasks (e.g., higher demands, dual tasks, increased number of targets, conjunction tasks) were more sensitive and could detect more cases (chronic/subclinical) than more simple versions (e.g., feature tasks) (Marshall et al, 1997;List et al, 2008;Erez et al, 2009;Van Kessel et al, 2013;Andres et al, 2019;Ten Brink et al, 2020;Villarreal et al, 2020).…”

“…The authors identified 13 studies, that investigated test batteries of CB versions of conventional tasks, including tasks similar to line bisection (Chiba et al, 2010;Jee et al, 2015), cancellation (Rabuffetti et al, 2002(Rabuffetti et al, , 2012, baking tray (Chung et al, 2016) or combinations of different types of tasks (Liang et al, 2007;Ulm et al, 2013;Pallavicini et al, 2015;Vaes et al, 2015;Mizuno et al, 2016;Ten Brink et al, 2016;Quinn et al, 2018;Morando et al, 2019). Our synthesis included 11 studies exploring visual search tasks such as static (Mizuno et al, 2016;Machner et al, 2018;Ten Brink et al, 2020), feature and conjunction (List et al, 2008;Erez et al, 2009), dynamic and dual tasks (Marshall et al, 1997;Deouell et al, 2005;Van Kessel et al, 2013;Andres et al, 2019;Villarreal et al, 2020). We detected five studies that observed different types of tasks such as the widely investigated Posner cueing paradigm (Rengachary et al, 2009), a neglect/extinction task (Vossel et al, 2010), a temporal order judgment (TOJ) task (Stigchel and Nijboer, 2017), a driving simulator task (Spreij et al, 2020) and a manual spatial exploration task (Pierce et al, 2021).…”

“…By carefully examining the data, it was found that CB functional (Pallavicini et al, 2015) and visual search tasks were shown to be more sensitive than CB versions of PnP tasks (Ten Brink et al, 2020). Moreover, combining different types of tasks can capture a wider aspect of neglect symptoms (Erez et al, 2009;Mizuno et al, 2016;Spreij et al, 2020).…”

“…Visual search and exploration tasks included measures based on false alarms/catch trials responses, target detection (capturing accuracy, detection rate/probability) and time (such as RT, search time and task duration); data analysis in these tasks was performed based on target position [e.g., left/right (L/R)] and task demands (e.g., level of difficulty, number of distractors) (Marshall et al, 1997;Deouell et al, 2005;List et al, 2008;Erez et al, 2009;Vossel et al, 2010;Rengachary et al, 2011;Van Kessel et al, 2013;Vaes et al, 2015;Mizuno et al, 2016;Machner et al, 2018;Andres et al, 2019;Ten Brink et al, 2020;Villarreal et al, 2020).…”

Computer-Based Assessment: Dual-Task Outperforms Large-Screen Cancellation Task in Detecting Contralesional Omissions

“…Patients with milder forms of the deficit, however, tend not to show omissions in cancellation tasks without distractors. To overcome this problem, task sensitivity has been enhanced by specifically adjusting the stimuli, for example, by increasing the target density and the relative salience of distractors (Rapcsak et al, 1989;Aglioti et al, 1997;Chatterjee et al, 1999;Sarri et al, 2009;Bickerton et al, 2011;Basagni et al, 2017;Ten Brink et al, 2020;Villarreal et al, 2020). To prevent compensation and to identify milder deficits, time limits are sometimes introduced (Priftis et al, 2019).…”