End of the line: Line bisection, an unreliable measure of approach and avoidance motivation

Approach motivation leads to greater left hemisphere activation, whereas an avoidant motivational state activates the right hemisphere. Recent research, which served as the basis for the current experiment, suggests line bisection provides a simple measure of approach/avoidance lateralisation. Findings from Experiment 1 indicated that the landmark task was sensitive enough to identify lateral asymmetries evoked by happy and angry faces; however, follow-up experiments failed to replicate this finding. When task instructions were slightly modified or when a mixed design was used, motivation did not influence landmark task performance. The use of images in lieu of faces also failed to produce a significant effect. Importantly, a straight replication of Experiment 1 produced a null result. Line bisection does not appear to be a suitable measure of lateralised approach/avoidance biases, possibly due to the high individual variability inherent in visuospatial biases. Implications for null hypothesis significance testing are also discussed.