Five experiments are reported. These demonstrate that, in bilingual subjects, Welsh digits take longer to articulate than their English equivalents, and this difference is paralleled by the finding that digit span in Welsh is significantly smaller than that in English. These differences are attributable to bilingual word-length differences, and it is this, rather than intellectual differences, which explains why the norms for Welsh children on the digit span test of the Welsh Children's Intelligence Scale are reliably less than those for the same age American children tested on the similar digit span procedure of the Wechsler Intelligence Scale for Children. These findings lead to the prediction that mental calculation in the Welsh language will be more difficult than that in English.

An interaction between translation and storage in working memory is demonstrated. This finding accords with the working memory formalization of Baddeley & Hitch (1974). It is shown that translation towards the language of preference is faster than that in the reverse direction.