Is there a Relationship between Task Demand and Storage Space in Tests of Working Memory Capacity?

Abstract

This paper considers working memory capacity, critically examining the hypothesis that counting span (the ability to count arrays of objects and store count totals) reflects a trade-off in resources available for processing and short-term storage. Previous evidence interpreted as favouring this hypothesis has confounded task difficulty with counting time. Experiment 1 validated a manipulation of the attentional demands of counting in which target objects were differentiated from non-targets by either a single feature (colour) or a feature conjunction (a combination of line orientations). The results confirmed that the two presentations involved qualitatively different attentional loads. Experiment 2 used these displays to compare counting span for children aged 6 to 11, both with and without an adjustment of target numerosity to control for differences in processing time. At all ages, span was lower when counting took longer, but there was no difference between feature and conjunction arrays once counting time was accounted for. These results argue against a resource trade-off interpretation of counting span. Rather, they support a hypothesis of resource-switching among children, implying that counting span acts as a measure of time-based forgetting.

Time Constraints and Resource Sharing in Adults' Working Memory Spans.

“…In all of these experiments, a higher number of retrievals:time ratio resulted in poorer recalls and lower working memory spans, even when the total duration of the intervening treatment was reduced (Experiments 5 and 6). This last result definitely rules out Towse and Hitch's (1995) task-switching model: Shorter treatments can lead to lower working memory spans. In accordance with our model, this fact suggests that participants switch their attention from processing to maintenance during the intervening activity and that the relative difficulty of this switching process determines what is called cognitive load.…”

“…To test their cognitive load hypothesis against Towse and Hitch's (1995) memory decay hypothesis, Barrouillet and Camos compared Turner and Engle's (1989) operation span with the baba span while holding the total duration of both tasks constant. As predicted, the authors observed that the processing component involving a higher cognitive load (i.e., operation solving) led to lower recall performance and that the operation span was lower than the baba span.…”

“…It could thus be argued that the cognitive load hypothesis holds only in children who lack the appropriate skills to perform the tasks efficiently. As soon as these skills are acquired, the putative cognitive load would no longer matter and the duration of the task would be the sole relevant factor for working memory spans, as predicted by the memory decay hypothesis (Towse & Hitch, 1995).…”

What limits working memory capacity?

“…Work along this line needs to flesh out in more detail how the resource limit is to be combined with the mechanisms of interference. (Baddeley et al, 1975;Schweickert & Boruff, 1986) Neo-Piagetian general resource model (Case et al, 1982) Feature model (Nairne, 1990) Limited-capacity trace-decay theory (Jensen, 1988;Salthouse, 1996) Multiple-resource model (Alloway et al, 2006;Logie, 2011) Interference model (Oberauer & Kliegl, 2001 Primacy model (Page & Norris, 1998) 3CAPS (Just & Carpenter, 1992) SOB (Lewandowsky & Farrell, 2008b) and SOB-CS (Oberauer, Lewandowsky, et al, 2012) Task-switching model (Towse & Hitch, 1995;Towse, Hitch, & Hutton, 2000) Slot model (Luck & Vogel, 2013;Cowan et al, 2012) Temporal-clustering-andsequencing model (Farrell, 2012) Computational phonological loop model (Burgess & Hitch, 1999 Resource models of visual WM Time-based resource-sharing model Camos et al, 2009) Note: Theories in the table were selected because they attribute the WM capacity limit unambiguously to decay, limited resources, or interference, respectively. Some theories of WM were not included because they combine two or three of the hypotheses, or make no clear assumptions about what causes the capacity limit.…”

Working memory span development: A time-based resource-sharing model account.

“…However, other aspects of our results questioned our model. First, it appeared that Towse and Hitch's (1995) task-switching model is more appropriate to account for working memory in preschoolers than the TBRS model. Second, the three main sources of development of working memory-processing efficiency, storage ability, and amount of available attention-are probably, as Bayliss et al (2005) demonstrated, more independent than the TBRS model assumes.…”