Table 1.
Commonly used working memory capacity tasks
| Task | Additional cognitive demand | Classification | Notes |
|---|---|---|---|
| Operation span (Turner & Engle, 1989) | Interwoven processing task (basic arithmetic) | Complex span | Verbal memoranda. Storage and processing tasks are independent. Tends to be less predictive than spatial WMC tasks for higher ability individuals which may be ameliorated by adding larger set sizes (Draheim et al., 2018) |
| Reading span (Daneman & Carpenter, 1980) | Interwoven processing task (reading comprehension) | Complex span | Verbal memoranda. Tends to be less predictive than spatial WMC tasks. Processing task may be tied to storage task (e.g., remember the last word of each passage) |
| Symmetry span (Unsworth et al., 2009) | Interwoven processing task (symmetry judgment) | Complex span | Spatial memoranda. Storage and processing tasks are independent |
| Rotation span (Kane et al., 2004) | Interwoven processing task (judge whether rotated letter is forward-facing or a mirror image) | Complex span | Spatial and bivalent memoranda. Storage and processing tasks are independent |
| Counting span (Case et al., 1982) | Interwoven processing task (simple counting) | Complex span | Numerical memoranda. Appropriate for young children. Processing task may be tied to storage task (e.g., remember the counts of each set of stimuli) |
| Running span (Pollack et al., 1959) | Continuous dropping of previously relevant information to accommodate new information | Updating | Correlates strongly with complex span tasks and loads onto same factor as complex span (Broadway & Engle, 2010; Shipstead et al., 2012a, b). Predicts incremental variance in Gf over complex span (Shipstead et al., 2014) |
| N-back (Kirchner, 1958) | Continuous dropping of previously relevant information to accommodate new information | Updating | Used widely in neuroscience research. Challenged as a measure of WMC due to weak correlations with complex span and does not load onto same factor as complex span (T. L. Harrison, 2017; Kane et al., 2007; Miller et al., 2009; Redick & Lindsey, 2013) |
| Mental counters (Larson & Saccuzzo, 1989) | Continuous dropping of previously relevant information to accommodate new information | Updating | Performance seems jointly attributable to WMC and Gf (Colom & Shih, 2004; Hicks et al., 2016; Mackintosh & Bennet, 2003) |
| Backwards span (Wechsler, 1939) | Mental transposition of memoranda during recall (report in reverse serial order as stimuli were presented) | Transposed Serial Recall | Combined with forward (simple) span in the WAIS-IV (Wechsler, 2008) to assess WMC. Results are mixed as to whether it assesses STM or WMC (Egeland, 2015; Engle et al., 1999; Hilbert et al., 2014; Oberauer et al., 2000; Rosen & Engle, 1997). St Clair-Thompson (2010) and St Clair-Thompson and Allen (2013) argue that backwards span is a WMC measure in children but a STM task in adults due to the relative difficulty of mental transposition |
| Letter-number sequencing | Mental transposition of memoranda during recall (report numbers in ascending order then letters in alphabetical order) | Transposed serial recall | Included in the WAIS-IV to assess WMC. Like backwards span, challenged as a measure of WMC as mental transposition during recall may not impose a sufficient cognitive load to prevent rehearsal (e.g., Egeland, 2015) |
| Nonselective visual arrays (Luck & Vogel, 1997) | Rapid visual presentation; attentional capture (with larger set sizes) | Change detection | Performance may be jointly attributable to WMC and attention control (Fukuda et al., 2016; Martin et al., 2021) |
| Selective visual arrays (Vogel & Machizawa, 2004) | Rapid visual presentation; attentional capture; selective attention | Change detection | Challenged as a measure of WMC as it is argued that individual differences in performance are primarily due to attentional factors (Draheim et al., 2021; Martin et al., 2021; see Fukuda et al., 2016; Vogel et al., 2005). This is discussed further in the section of this article on the measurement of attention control. |
WMC Working memory capacity, STM short-term memory, WAIS Wechsler Adult Intelligence Scale. Note that this is by no means an exhaustive list and, in general, if a procedure involves the immediate recall of to-be-remembered information, that task or procedure has almost certainly been considered a measure of working memory capacity by someone. Critically, working memory tasks, like tests of most traits, are not all interchangeable, and thus caution must be exercised when evaluating research in which different tasks are used to measure the same underlying ability or construct