title: Left-handers' struggle in a rightward wor(l)d: The relation between horizontal spatial bias and effort in directed movements.
abstract: Five studies investigated the role of handedness and effort in horizontal spatial bias related to agency (Spatial Agency Bias, SAB). A Pilot Study (n = 33) confirmed the basic assumption that rightward writing requires greater effort from left- than from right-handers. In three studies, Italian students (n = 591 right-handed, n = 115 left-handed) were found to start drawings on the left, proceeding rightward (Study 1a, 1b), and to draw moving objects with a rightward orientation in line with script direction (Study 1c). These spatial asymmetries were displayed stronger by left- than by right-handed primacy school children, arguably due to the greater effort involved in learning how to write in a rightward fashion. Once writing has become fully automatic (high school) right- and left-handed students showed comparable spatial bias (Study 1c). The hypothesized role of effort was tested explicitly in Study 2 in which 99 right-handed adults learned a new (leftward) spatial trajectory through an easy or difficult motor exercise. The habitual rightward bias was reliably reduced, especially among those who performed a difficult task requiring greater effort. Together, findings are largely in line with the body specificity hypothesis (Casasanto, 2011 ) and suggest that spatial asymmetries are learned and unlearned most efficiently through effortful motor exercises.
authors.affiliation: a Department of Developmental and Social Psychology , University of Padova , Padova , Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Suitner
authors.affiliation: a Department of Developmental and Social Psychology , University of Padova , Padova , Italy.
authors.forename: Anne
authors.initials: A
authors.lastname: Maass
authors.affiliation: a Department of Developmental and Social Psychology , University of Padova , Padova , Italy.
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Bettinsoli
authors.affiliation: a Department of Developmental and Social Psychology , University of Padova , Padova , Italy.
authors.forename: Luciana
authors.initials: L
authors.lastname: Carraro
authors.affiliation: a Department of Developmental and Social Psychology , University of Padova , Padova , Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Kumar
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D005260:Female; D007839:Functional Laterality; D006225:Hand / Q000502:physiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010865:Pilot Projects; D011597:Psychomotor Performance / Q000502:physiology; D013028:Space Perception / Q000502:physiology; D014956:Writing; D055815:Young Adult
keywords: Handedness; asymmetry; body specificity; horizontal spatial bias; script direction; visual perception