Line Bisection Test
Background
The Line Bisection Task (LBT)bis predominantly used as a neuropsychological screening tool for unilateral spatial neglect (USN)—a condition where a person fails to attend to or perceive things on one side of space, most commonly after a right-hemisphere stroke or brain injury. The task is simple: participants receive several horizontal lines and are asked to mark the midpoint on each one.
Theodor Axenfeld first described an early version of the task in 1894 as a method to diagnose 'hemianopia' (blindness in half of the visual field). The test was then standardized by Thomas Schenkenberg and colleagues in 1980 for clinical use to screen for right-hemisphere brain damage which results in a significant, measurable right-bias in midpoint markings. Interestingly, around the same time Dawn Bowers and Kenneth Heilman (1980) showed that healthy brains on the other hand tended to slightly favor the left side, resulting in a sort of right-space 'pseudoneglect'.
The LBT is further used in movitation research. Kyle Nash and his colleagues argued that people with high approach motivation (e.g., feeling eager, focused, or drawn toward a specific goal) show greater brain activity in their left frontal hemisphere which should be measurable by a right-shift bias in the LBT. Their experimental results from 2010 supported that the LBT could be used as an efficient, yet unobtrusive behavioral neuroscience measure of approach motivation.
Task Procedure
The Millisecond Line Bisection Task provides participants with up to 14 horizontal lines of different lengths, with midpoints staggered (default = 6). Participants are asked to mark (with mouse click or touch) the midpoints of each line with a small red mark. The position of the red mark can be changed. All marks have to be placed before a 'Done' button appears. Participants are specifically instructed not to measure the lines.
What it Measures
The Line Bisection Task is a measure of spatial attention allocation
Psychological domains
- Visuospatial Attention: The cognitive ability to selectively process, prioritize, and respond to visual information in a specific area of space
- Attentional Lateralization: Asymmetry in allocation of spatial attention
Main Performance Metrics
- Left Error Score: Proportion of left side errors
- Error Distance: mean pixel and mm error distance
Psychiatric Conditions
The following patient groups are routinely tested with Line Bisection Tasks
- Traumatic Brain Injury (TBI)
- Stroke
A behavioral measure of relative cerebral hemisphericity that is based on people's line bisection performance.
References
Search Google Scholar for peer-reviewed, published research using the Inquisit Line Bisection Test.
Jewell, G.,&McCourt, M. E. (2000). Pseudoneglect: A review and metaanalysis of performance factors in line bisection tasks. Neuropsychologia, 38, 93–110.
Savazzi, S., Posteraro, L., Veronesi, G., & Mancini, F. (2007). Rightward and leftward bisection biases in spatial neglect: two sides of the same coin? Brain (London, England : 1878), 130(8), 2070–2084. https://doi.org/10.1093/brain/awm143
Nash, K., Mcgregor, I., & Inzlicht, M. (2010). Line bisection as a neural marker of approach motivation. Psychophysiology, 47(5), 979–983. https://doi.org/10.1111/j.1469-8986.2010.00999.x