Impairment of the visuo-spatial sketch pad.

A case study is presented of a female patient, ELD, who has difficulty in the immediate recall of short sequences of visuo-spatial material following a right-hemisphere aneurysm. Despite poor performance on tasks such as the Brooks Matrix and the Corsi Blocks, ELD is good at the immediate serial recall of letters even when presentation modality is visual and shows effects of phonological similarity and articulatory suppression. This pattern of performance represents a double dissociation from that which has been observed with the short-term memory patient PV (Vallar & Baddeley, 1984), who is extremely poor at serial recall of verbal material but shows no visual memory impairment. It is argued that ELD has an impairment to the visuo-spatial component of working memory (Baddeley, 1986) in the absence of any phonological loop deficit. Further investigation reveals that ELD performs poorly on mental rotation tasks and finds it difficult to use imagery mnemonics, but has no difficulty in retrieving visuo-spatial information from long-term memory so long as it was learnt before her illness.