Investigating effects of divided attention at test on memory accessibility and precision in a continuous report paradigm

Previously reported tests for effects of dividing attention during long-term memory (LTM) retrieval have yielded inconclusive findings. This may be due to most prior work relying on categorical recall or recognition measures, which lack sufficient precision to detect subtle effects. Here, we provide the first test of divided attention effects on LTM retrieval using a continuous report paradigm, allowing retrieval errors to be measured with greater precision. In Experiment 1, participants (N = 44) encoded object-orientation associations and later retrieved object orientations under either full or divided attention while performing a visual search task. On each trial, error was computed as the difference between the reported and studied orientations of the tested object. Dividing attention during retrieval resulted in increased errors. To characterize the nature of these errors, we analyzed error distributions using both a standard mixture model (SMM) and the Target Confusability Competition (TCC) model. The SMM showed that divided attention reduced memory accessibility, while the precision of retrieved memories remained unaffected. The TCC model provided better fits and similarly indicated reduced memory strength under divided attention. Experiment 1 included an additional working memory load due to withholding the divided attention task response throughout the main retrieval task; Experiment 2 (N = 44) replicated the main findings while eliminating this load by having participants respond to the secondary task before the retrieval response. Together, these findings show that continuous report measures reveal costs of divided attention on LTM retrieval that primarily reflect reduced retrieval success or strength rather than reduced representational precision.