Reducing alertness does not affect line bisection bias in neurotypical participants

Published: 24 November 2022| Version 2 | DOI: 10.17632/by5tzcp9sj.2
Stefan Smaczny,


This is a set of .csv data files as well as R analysis code for the project stated in the title. Participants were required to bisect 32 horizontal lines of varying size and shape (see McIntosh et al., 2005; 2017) on a computer screen using their mouse. This was done with and without spatial cues (shortly displayed, red, vertical lines at one end of the horizontal line), followed by a vigilance task, followed by the line bisection task again. The vigilance task was a 50-minute task in which a horizontal line moved up and down randomly; whenever it reached a certain threshold (i.e., it crossed a static horizontal line in the top half of the screen), participants were meant to push the space bar as quickly as possible. On average, participants' reaction times decreased over the vigilance task, suggesting a reduction in alertness. Similarly, for about half the sample this reduction was also indicated by the Stanford Sleepiness Scale. For the other half of the sample, no such data could be used, as the Stanford Sleepiness Scale was translated incorrectly. While the reduction in alertness did not have an effect on a measure of spatial attention (endpoint weightings bias, EWB), it did show an effect on a measure of general attention, endpoint weightings sum (EWS). McInt_Vig_04-20.csv and McInt_Vig_cue_04-20.csv contain, for each participant, all bisection measures derived without cues and with cues, respectively. McInt_Vig_vig.csv contains the reaction times of participants to the vigilance task. Edit: Added raw data



Universitatsklinikum Tubingen Neurologische Universitatsklinik, Brunel University Department of Life Sciences


Cognitive Psychology, Attention, Spatial Ability-Cognition


Deutsche Forschungsgemeinschaft

KA 1258/23-1 AOBJ 632333

Brunel Research Initiative & Enterprise Fund