Chunking in tonal contexts: Information compression during serial recall of visually presented musical notes

Chunking is defined as information compression by means of encoding meaningful units. To advance the understanding of chunking in musical memory, the present study tested characteristics of melodic sequences that might enable a parsimonious memory representation, namely, the presence of a clear tonal context and of melodic cells with clear labels. Musical note symbols, which formed either triads (Experiment 1) or cadences (Experiment 2), were presented visually and sequentially to musically experienced participants for immediate serial recall. The melodic sequences were varied on the within-participant factors list length (long vs. short list) and tonal structure (chunking-supportive vs. chunking-obstructive). Chunking-supportive sequences contained tones from a single diatonic key that formed melodic cells with a clear label, such as “C major triad”. Transitional errors showed that participants grouped notes into melodic cells. Mixed logistic regression modeling revealed that recall was more accurate in chunking-supportive sequences and that this advantage was more pronounced for more experienced participants in the long list length condition of Experiment 2. The findings suggest that a clear tonal context and melodic cells with clear labels benefit chunking in melodic processing, but that the subtleties of the process are additionally influenced by type, size, and number of melodic cells.

How Does Semantic Knowledge Impact Working Memory Maintenance? Computational and Behavioral Investigations

It is now firmly established that long-term memory knowledge, such as semantic knowledge, supports the temporary maintenance of verbal information in Working Memory (WM). This support from semantic knowledge is well-explained by models assuming that verbal items are directly activated in long-term memory, and that this activation provides the representational basis for WM maintenance. However, the exact mechanisms underlying semantic influence on WM performance remain poorly understood. We manipulated the presence of between-item semantic relatedness in an immediate serial recall task, by mixing triplets composed of semantically related and unrelated items (e.g. leaf – tree – branch – wall – beer – dog; hand – father – truck – cloud – sky – rain). Compared to unrelated items, related items were better recalled, as had been classically observed. Critically, semantic relatedness also impacted WM maintenance in a complex manner, as observed by the presence of proactive benefit effects on subsequent unrelated items, and the absence of retroactive effects. The complexity of these interactions is well-captured by TBRS*-S, a decay-based computational architecture in which the activation occurring in long-term memory is described. The present study suggests that semantic knowledge can be used to free up WM resources that can be reallocated for maintenance purposes, and supports models postulating that long-term memory knowledge constrains WM maintenance processes.

Towards a Theory of Working Memory

Working memory provides a medium for building and manipulating new representations that control our thoughts and actions. To fulfil this function, a working memory system needs to meet six requirements: (1) it must have a mechanism for rapidly forming temporary bindings to combine elements into new structures; (2) it needs a focus of attention for selectively accessing individual elements for processing; (3) it must hold both declarative representations of what is the case, and procedural representations of how to act on the current situation; (4) it needs a process for rapid updating, including rapid removal of outdated contents. Moreover, contents of working memory (5) need to be shielded from interference from long-term memory, while (6) working memory should be able to use information in long-term memory when it is useful. This chapter summarizes evidence in support of these mechanisms and processes. It presents three computational models that each implement some of these mechanisms, and explains different subsets of empirical findings about working memory: the SOB-CS model accounts for behaviour in tests of immediate serial recall, including complex-span tasks. The interference model explains data from a common test of visual working memory, the continuous-reproduction task. The set-selection model explains how people learn memory sets and task sets, how these sets are retrieved from long-term memory, and how these mechanisms enable switching between memory sets and task sets.

Lexical connectivity effects in immediate serial recall of words

In four experiments, we tested whether immediate serial recall is influenced by a word’s degree centrality, an index of lexical connectivity. Words of high degree centrality are associated with more words in free association norms than those of low degree centrality. Experiment 1 reanalysed four existing datasets (collected for other purposes) to explore the effect of degree centrality in scrambled wordlists. Results indicated that high-degree (vs. low-degree) words are advantaged across all serial positions, independently of other variables including word frequency. Experiment 2 replicated this finding using an expanded stimulus set. Experiment 3 used pure lists with each list containing high- or low-degree words only. Once again, high-degree words were better recalled across all serial positions, and this could not be explained by other psycholinguistic variables. Experiment 4 used alternating lists, within which high- and low-degree words alternated. High-degree words were no longer advantaged overall. Instead, recall of low-degree words was facilitated when neighboured by high-degree words. We conclude that degree centrality is a distinct variable that affects serial recall and consider its influence both as an item-level characteristic that reflects how accessible a word is and as an inter-item property that captures how well associative links can be formed between words.

Lexical connectivity effects in immediate serial recall of words

In four experiments, we tested whether immediate serial recall is influenced by a word’s degree centrality, an index of lexical connectivity. Words of high degree centrality are associated with more words in free association norms than those of low degree centrality. Experiment 1 reanalysed four existing datasets (collected for other purposes) to explore the effect of degree centrality in scrambled wordlists. Results indicated that high-degree (vs. low-degree) words are advantaged across all serial positions, independently of other variables including word frequency. Experiment 2 replicated this finding using an expanded stimulus set. Experiment 3 used pure lists with each list containing high- or low-degree words only. Once again, high-degree words were better recalled across all serial positions, and this could not be explained by other psycholinguistic variables. Experiment 4 used alternating lists, within which high- and low-degree words alternated. High-degree words were no longer advantaged overall. Instead, recall of low-degree words was facilitated when neighboured by high-degree words. We conclude that degree centrality is a distinct variable that affects serial recall and consider its influence both as an item-level characteristic that reflects how accessible a word is and as an inter-item property that captures how well associative links can be formed between words.

Serial recall

Serial memory refers to the ability to recall a novel sequence of items or events in the correct order. In the laboratory, the dominant tool used to assess this mental faculty is the immediate serial recall (hereafter, ‘serial recall’) task in which participants are given a sequence of typically verbal, visual, or spatial items that they must subsequently recall in their original presentation order. Serial recall is a deceptively simple task—the apparent ease with which people accomplish it masks the wealth and complexity of findings this task has generated, and the computational theories that have been developed to account for them. In this chapter, I review benchmark findings of serial recall that have been observed across the verbal, visual, and spatial short-term memory domains, and I interpret them with reference to the core mechanisms embodied in contemporary computational theories of serial recall. This analysis identifies four mechanisms that are common to the three content domains—namely, position marking, a primacy gradient, competitive queuing, and response suppression. Additionally, evidence suggests that in verbal serial recall both the encoding and retrieval of items is sensitive to item similarity—similarity-sensitive encoding and retrieval—and that item retrieval is accompanied by output interference. By contrast, in visual and spatial serial recall there is evidence for similarity-sensitive retrieval, but the relevant empirical observations that evince similarity-sensitive encoding and output interference are yet to be studied in the visual and spatial domains. I conclude by outlining some challenges for future research.

Strategy Use on Clinical Administrations of Short-Term and Working Memory Tasks

Experimental measures of working memory that minimize rehearsal and maximize attentional control best predict higher-order cognitive abilities. These tasks fundamentally differ from clinically administered span tasks, which do not control strategy use. Participants engaged in concurrent articulation (to limit rehearsal) or concurrent tapping (to limit attentional refreshing) during forward and backward serial recall with each of three distinct stimulus sets: digits, line drawings of common objects, and images of nonsense symbols. The span tasks used common clinical stopping and scoring procedures. Scores were highest for digits and lowest for novel symbols in all combinations of direction and concurrent task. Furthermore, concurrent articulation and concurrent tapping interfered with backward recall to the same degree. Together, these findings indicate that clinically administered immediate serial recall tasks depend on both rehearsal and long-term lexical knowledge making it difficult to use these tasks to separate problems in language ability from problems in attention.

Tactile memory Ranschburg effects under conditions of concurrent articulation

In a single experiment, we investigate the Ranschburg effect for tactile stimuli. Employing an immediate serial recall (ISR) procedure, participants recalled sequences of six rapidly presented finger stimulations by lifting their fingers in the order of original stimulation. Within-sequence repetition of an item separated by two intervening items resulted in impaired recall for the repeated item (the Ranschburg effect), thus replicating the findings of Roe et al. Importantly, this impairment persisted with concurrent articulation, suggesting that the Ranschburg effect is not reliant upon verbal recoding. These data illustrate that the Ranschburg effect is evident beyond verbal memory and further suggest commonality in process for both tactile and verbal order memory.