DO THE HANDS TALK ON MINDS BEHALF - DIFFERENCES IN LANGUAGE ABILITY BETWEEN LEFT-HANDED AND RIGHT-HANDED CHILDREN

Two hundred seventy children of school age, 135 of whom were left-hand ed and an equivalent number of whom were right-handed, have been exami ned in the present study using a test battery of nine language ability measures: Vocabulary, Similarities, Comprehension (WISC-R), Deductive Reasoning, Inductive Reasoning, Sentence Completion, Comprehension of Sentential Semantics, Comprehension of Syntax, and Text Processing. T he data analysis has indicated that: (1) One-factor solution applies b oth to the right- and left-handed population according to Standard Err or Scree Method (Zoski & Jurs, 1996) with regard to language ability m easures. (2) Handedness discriminates between right-handers (superior) and left-handers (inferior) in language ability. (3) There have been subgroups of left-handed children who differ in language ability distr ibution compared with right-handed children according to Hierarchical Cluster Analysis. (4) Extreme versus mild bias to hand preference and hand skill do not differentiate performance subgroups neither within t he left-handed nor within the right-handed main group. (5) Sex and fam ilial sinistrality do not affect performance. The results are discusse d in relation to (a) ''human balanced polymorphism'' theory advocated by Annett (mainly Annett, 1985, 1993a; Annett & Manning, 1989), (b) po tential pathology (mainly Bishop, 1984, 1990a; Coren & Halpern, 1991; Satz, Orsini, Saslow & Henry, 1985) and ''developmental instability'' (Yeo, Gangestad & Daniel, 1993), and delay of left-hemisphere maturati on in left-handed individuals (Geschwind & Galaburda, 1985a,b, 1987), by pointing out the strength and weaknesses of these theoretical appro aches in accounting for the present data, (C) 1998 Academic Press.