Temporal isolation effects in immediate recall

Three experiments examined temporal isolation effects (TIEs), the recall advantage for stimuli separated by increased inter-stimulus intervals. Prior research suggests that TIEs are observed in immediate free recall (IFR) using longer lists, but are weaker or absent in immediate serial recall (ISR) using shorter lists. Using digit-filled intervals to reduce rehearsal, IFR and ISR benefitted overall from longer pre-item intervals and shorter post-item intervals, using lists of 7, 17, and 5 words (Experiments 1–3, respectively). Consistent with a grouping account, the first words recalled were often preceded by longer pre-item intervals and transitions tended to be between neighboring items separated by shorter intervals. Using 7-item lists with unfilled intervals (Experiment 3), both IFR and ISR benefitted from longer post-item intervals (possibly due to rehearsal), and once the first responses were removed, there was no effect of pre-item interval on either task. These similar findings encourage the theoretical integration of ISR and IFR.