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.

The Role of Hand Movement in Spatial Serial Order Memory

Research on serial order memory has traditionally used tasks where participants passively view the items. A few studies that included hand movement showed that such movement interfered with serial order memory. In the present study of three experiments, we investigated whether and how hand movements improved spatial serial order memory. Experiment 1 showed that manual tracing (i.e., hand movements that traced the presentation of stimuli on the modified eCorsi block tapping task) improved the performance of backward recall as compared to no manual tracing (the control condition). Experiment 2 showed that the facilitation effect resulted from voluntary hand movements and could not be achieved via passive viewing of another person’s manual tracing. Experiment 3 showed that it was the temporal, not the spatial, signal within manual tracing that facilitated spatial serial memory.

The effects of transcranial direct current stimulation on within- and cross-paradigm transfer following multi-session backward recall training

Transcranial direct current stimulation (tDCS) has been shown to enhance the efficacy and generalisation of working memory (WM) training, but there has been little systematic investigation into how coupling task-specific WM training with stimulation impacts more specifically on transfer to untrained tasks. This randomised controlled trial investigated the boundary conditions to transfer by testing whether firstly the benefits of training on backward digit recall (BDR) extend to untrained backward recall tasks and n-back tasks with different materials, and secondly which, if any, form of transfer is enhanced by tDCS. Forty-eight participants were allocated to one of three conditions: BDR training with anodal (10 min, 1mA) or sham tDCS, or visual search training with sham tDCS, applied over the left dorsolateral prefrontal cortex. Transfer was assessed on within- (backward recall with digits, letters, and spatial locations) and cross-paradigm (n-back with digits and letters) transfer tests following three sessions of training and stimulation. On-task training gains were found, with transfer to other backward span but not n-back tasks. There was little evidence that tDCS either enhanced the rate or magnitude of on-task training or transfer gains. These findings indicate that training enhances paradigm-specific processes within WM, but that tDCS does not enhance these gains.

Evidence for separate backward recall and n-back working memory factors: A large-scale latent variable analysis

There is growing interest in understanding what constrains transfer following working memory (WM) training with recent studies investigating what limits transfer within and across different WM paradigms. The primary aim of the current study was to conduct a large-scale latent variable analysis to identify distinct properties between WM tasks to provide further insight into task features that might constrain transfer following training. A secondary aim was to explore how the resulting WM factor(s) were linked to Gf. Participants (N = 703) completed multiple web-based versions of n-back and backward recall tasks and a test of non-verbal reasoning. The memory tasks contained different memoranda that varied across (spatial or verbal material) and within (verbal digits or letters) domain, allowing the variance specific to task content and paradigm to be assessed. The data were best-captured by two distinct but related backward recall and n-back constructs, each linked to a separate reasoning factor, in comparison to other plausible model constructions (including a single WM factor, two-factor domain, and three-factor materials model). This suggests these WM tasks measure distinct paradigm-specific processes, but share common variance with one another and with a reasoning task. The benefits of cognitive training targeting a single paradigm are therefore likely to be limited to the same paradigm. For broader transfer it will be necessary to target what is shared across paradigms.