The centre is not in the middle: Evidence from line and Italian word bisection.

English and German readers have been shown to mark a position to the left of the true centre as the subjective
midpoint in word bisection. This effect resembles a well-known phenomenon observed with the
bisection of solid lines (pseudoneglect), although this behavioural similarity does not imply a common
origin. The purpose of the present study was twofold: on the one hand, to investigate the perceptual
and lexical features that influence the bisection of Italian orthographic strings and, on the other hand, to
investigate whether identical or partially independent processing mediate bisection of line and orthographic
stimuli. Five experiments were carried out to explore to what extent stimulus type (lines, words,
pseudowords, consonant strings, symbols), stimulus length (from 3 to 13 characters), list context (pure
and mixed), and written word frequency (high and low) affected the bisection performance. The results
showed that list context modulated the processing similarities across different materials and that word
frequency failed to influence the magnitude of the bisection bias.
More critically, across all five experiments, the results showed different effects for solid lines versus
orthographic material. Lines were always bisected to the left, independent of length and list context.
By contrast, a crossover effect emerged with orthographic material; for long stimuli (above five letters)
the bias was consistently to the left, while short stimuli showed a consistent rightward bias.
The results indicate that manual bisection involved partly different cognitive mechanisms during word
and line perception and that this may depend on the characteristics of the stimuli (words/discrete vs.
lines/continuous).