title: Parallel effects of memory set activation and search on timing and working memory capacity.
abstract: Accurately estimating a time interval is required in everyday activities such as driving or cooking. Estimating time is relatively easy, provided a person attends to it. But a brief shift of attention to another task usually interferes with timing. Most processes carried out concurrently with timing interfere with it. Curiously, some do not. Literature on a few processes suggests a general proposition, the Timing and Complex-Span Hypothesis: A process interferes with concurrent timing if and only if process performance is related to complex span. Complex-span is the number of items correctly recalled in order, when each item presented for study is followed by a brief activity. Literature on task switching, visual search, memory search, word generation and mental time travel supports the hypothesis. Previous work found that another process, activation of a memory set in long term memory, is not related to complex-span. If the Timing and Complex-Span Hypothesis is true, activation should not interfere with concurrent timing in dual-task conditions. We tested such activation in single-task memory search task conditions and in dual-task conditions where memory search was executed with concurrent timing. In Experiment 1, activating a memory set increased reaction time, with no significant effect on time production. In Experiment 2, set size and memory set activation were manipulated. Activation and set size had a puzzling interaction for time productions, perhaps due to difficult conditions, leading us to use a related but easier task in Experiment 3. In Experiment 3 increasing set size lengthened time production, but memory activation had no significant effect. Results here and in previous literature on the whole support the Timing and Complex-Span Hypotheses. Results also support a sequential organization of activation and search of memory. This organization predicts activation and set size have additive effects on reaction time and multiplicative effects on percent correct, which was found.
authors.affiliation: Department of Psychological Sciences, Purdue University West Lafayette, IN, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Schweickert
authors.affiliation: École de Psychologie, Université Laval Québec, QC, Canada.
authors.forename: Claudette
authors.initials: C
authors.lastname: Fortin
authors.affiliation: Department of Psychological Sciences, Purdue University West Lafayette, IN, USA.
authors.forename: Zhuangzhuang
authors.initials: Z
authors.lastname: Xi
authors.affiliation: École de Psychologie, Université Laval Québec, QC, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Viau-Quesnel
keywords: activation; additive factor method; complex memory span; memory search; retrieval; selective influence; time production; working memory capacity