The most influential model of working memory (WM) defines four of its
components: the central executive, visuospatial sketchpad, phonological
loop and episodic buffer. WM has been shown to be notably involved in
linguistic processing. Nevertheless, the nature of the interaction of
lexical-semantic retrieval with WM components is still obscure. We
conducted a study in which subjects completed verbal fluency tasks (VF) and
were subjected to a neuropsychological assessment where three WM
components were tested: the central executive, visuospatial sketchpad and
episodic buffer. We chose verbal fluency because it excludes noise from
linguistic context.
Firstly, we differentiated between lexical-semantic categories with more
and less automatic semantic links and thus more or less automatic retrieval
processes. Secondly, we relied on models of embodied semantics which
predict considerable involvement of visual and spatial information in
lexical-semantic processing. The study recruited 20 healthy subjects, ages
20–31 (M=9, F=11). In the verbal fluency (VF) tasks subjects were to name
as many words in 60 s in the categories: animals and trees (category VF),
things one can do in the house (action VF), K, M and P (phonemic VF). We
calculated clustering and switching. The CANTAB battery was administered
for the neuropsychological assessment. Tests included the Spatial Working
Memory (visuospatial processing and strategy), the Stockings of
Cambridge (spatial
planning), the Attention Switching Task, the Paired Associates Learning
(visual episodic memory), and Delayed Matching to Sample (visual
recognition memory). Our results suggest that visual information recall is
an essential component in all verbal fluency tasks and that it is more
linked to clustering than switching. Furthermore, our results confirm the
hypotheses that different categories have different amounts of automatised
links between concepts. Tree fluency was positively correlated with
Attention Switching Task and Paired Associates Learning. Animal fluency was
not. Action fluency was further positively correlated with Spatial Working
Memory and Attention Switching Task. Thus, different WM components are
involved in different verbal fluency tasks.
