Distinctive items are salient during encoding: Delayed judgements of learning predict the isolation effect

Abstract

Three experiments examined the role of salience in predicting superior memory for incongruent or odd items (the isolation effect). We tested the hypothesis that encoding salience emerges over the course of the encoding episode and predicts the isolation effect. In Experiment 1 participants studied lists of unrelated items and lists of categorized items containing an isolated item (from a different semantic category) that was presented either early or late in the list. Participants made delayed judgements of learning (JOLs) for studied items and were then given a free recall test. Results showed that participants had superior recall for the isolated items regardless of their list position and that delayed JOLs predicted this effect for both early and late isolation conditions. Experiment 2 replicated this delayed JOL effect using a different isolation paradigm that used only a single study list. Experiment 3 examined the specific mechanism by which isolated items become salient over the course of encoding and demonstrated that isolated items become salient as knowledge of the list structure unfolds. Results from these studies suggest that isolated items become salient over the course of the study episode, and that this salience predicts the isolation effect in memory.

Revisiting von Restorff’s early isolation effect

“…In fact, detecting conceptual changes appears to require considerable attentional resources. When words are isolated early in a series (before list structure is apparent), participants may fail to notice conceptual contrasts unless specifically directed to by the task (as in the delayed JOL and immediate category verification tasks of Geraci & Manzano, 2010). However, Experiment 2 suggests that the difference between a twodigit number and a word is automatically encoded.…”

“…Simple conceptual differences between isolates and background items are not sufficient to produce an early isolation effect. To observe the early isolation effect, researchers must employ differences that are easily or automatically encoded such as words versus numbers, or they must use processing tasks that highlight target/background contrasts such as the delayed JOLs employed by Geraci and Manzano (2010) and Smith and Hunt (2016). Smith and Hunt (2016) argued that delayed JOLs enhance processing of categorical information, thereby increasing the likelihood of a conceptual isolation effect.…”

“…In the Kelley and Nairne (2001) study, the position of the isolate was systematically varied across all six serial positions in their lists. Geraci and Manzano (2010) placed the early isolates in one of the first four list positions.…”

Short- and long-lasting consequences of novelty, deviance and surprise on brain and cognition

“…The Novelty Effect consists of better recognition memory for new items than for items that were previously familiarized in a preceding phase (Kormi-Nouri et al, 2005;Tulving et al, 1994;Tulving and Kroll, 1995). The second is the Von Restorff effect, which denotes better memory for words presented in a deviant, novel font than for words presented in a standard font (Bruce and Gaines, 1976;Geraci and Manzano, 2010;Von Restorff, 1933;Schmidt, 1985), and for objects presented in novel rather than standard colors (Kishiyama et al, 2004(Kishiyama et al, , 2009. Interestingly, the Von Restorff effect is further enhanced by the D1/D2 receptor agonist apomorphine in humans , and is reduced in Parkinson's patients that have abnormalities in dopaminergic functioning .…”

Does the isolation effect require attention?

“…This supports the idea that participants would not be immediately aware of an item's distinctiveness when it is presented early in the list. Geraci and Manzano (2010), however, asked participants to make salience judgments after a delay (i.e., the salience judgment for an item was not made until two additional list items had been presented). They demonstrated higher salience ratings for both early and late isolates when the judgment was made after a delay.…”