Simple and Complex Working Memory Tasks Allow Similar Benefits of Information Compression

Abstract

Complex working memory span tasks were designed to engage multiple aspects of working memory and impose interleaved processing demands that limit the use of mnemonic strategies, such as chunking. Consequently, the average span is usually lower (4 ± 1 items) than in simple span tasks (7 ± 2 items). One possible reason for the higher span of simple span tasks is that participants can take advantage of the spare time to chunk multiple items together to form fewer independent units, approximating 4 ± 1 chunks. It follows that the respective spans of these two types of tasks could be equal (at around 4 ± 1) if stimulus lists exclusively used nonchunkable stimulus items. To manipulate the chunkability of the stimulus lists, our method involved a measure of their compressibility, i.e., the extent to which a pattern exists that can be detected and used as a basis of chunk formation. We predicted an interaction between the types of tasks and chunkability/compressibility, supporting a single higher span for the condition in which a simple span task was combined with chunkable items. The three other conditions were predicted to prevent chunking processes, either because the interleaved processing task did not allow any chunking process to occur or because the noncompressible material inherently limited the chunkability of information. The prediction that chunking is important solely in simple spans was not confirmed: Effects of information compression contributed to performance levels to a similar extent in both tasks according to a theoretically-based metric. This result suggests that i ) complex span tasks might overestimate storage capacity in general, and ii ) the difference between simple and complex span performance levels must rest in some mechanism other than prevention of a chunking strategy by the interleaved processing task in complex span tasks.

Speech production factors and verbal working memory in children and adults with developmental language disorder

“…The role of compression is dynamic (Chekaf et al, 2018), playing a greater role supporting recall as task demands increase. For typical adults, compression is not demanding of cognitive processing resources (Mathy et al, 2018), but may be for individuals with DLD (Montgomery et al, 2018). At peak task demands, participants with DLD may have been more constrained by efforts to divide their attention between storage and compression on the one hand, and processing on the other hand, resulting in the attenuated benefit of PA on compression.…”

“…Phonological activation may also facilitate word recall due to compressibility. Studies of nonverbal WM (Chekaf, Gauvrit, Guida, & Mathy, 2018;Mathy, Chekaf, & Cowan, 2018) show that longer sequences of items can be recalled if their complexity can be simplified by identifying features shared among the items. In a verbal complex span task, phonological activation may enhance encoding and thus the ability to recognize phonological patterns within and among target words, aiding compressibility.…”

“…Recognizing such phonological patterns in complex span tasks may require the ability to effectively switch attention between the processing task and compression (to aid storage). Studies of typical adults have found that compression processes may be fairly automatic (Mathy et al, 2018) whereas they may be more demanding of attentional resources for children with DLD (Montgomery et al, 2018).…”

Two Year Progression of Working Memory Impairments In Early Relapsing-Remitting Multiple Sclerosis: Appraisal of Working Memory Profiles And Measurement Sensitivity

“…Broadly, practice effects are a consequence of the unavoidable implication of long-term memory that occurs naturally upon engagement in a task or activity. This engagement may result in long term consolidation of measure speci c items due to rehearsal, general test familiarity, and/or the development and retention of memory devices such as grouping individual pieces of information into larger units (chunking) 53 ; this device is commonly used on the CVLT (classifying related words into groups: animals, transport, vegetable, furniture) 54 , and digit span measures (grouping of individual numbers into large numbers) 55 . While the OM n-back task was not free from practice effects (i.e.…”

Assessing working memory in general education students for ADHD detection

“…Complex span tasks interleave a memory task (e.g., remember a set of items in the correct order) with a secondary processing task (e.g., judge the correctness of equations). Consequently, the average span in these tasks is usually lower (4 ± 1 items) than in simple span tasks (7 ± 2 items) (Mathy, Chekaf, & Cowan, 2018), which only include the memory component (Unsworth, Redick, Heitz, Broadway, & Engle, 2009). Additionally, n-back task has been one of the most popular experimental paradigms for functional neuroimaging studies of working memory.…”