Confidence in Recognition Memory for Words: Dissociating Right Prefrontal Roles in Episodic Retrieval

Abstract

We used event-related functional magnetic resonance imaging (efMRI) to investigate brain regions showing differential responses as a function of confidence in an episodic word recognition task. Twelve healthy volunteers indicated whether their old-new judgments were made with high or low confidence. Hemodynamic responses associated with each judgment were modeled with an "early" and a "late" response function. As predicted by the monitoring hypothesis generated from a previous recognition study [Henson, R. N. A., Rugg, M. D., Shallice, T., Josephs, O., & Dolan, R. J. (1999a). Recollection and familiarity in recognition memory: An event-related fMRI study. Journal of Neuroscience, 19, 3962-3972], a right dorsolateral prefrontal region showed a greater response to correct low- versus correct high-confidence judgements. Several regions, including the precuneus, posterior cingulate, and left lateral parietal cortex, showed greater responses to correct old than correct new judgements. The anterior left and right prefrontal regions also showed an old-new difference, but for these regions the difference emerged relatively later in time. These results further support the proposal that different subregions of the prefrontal cortex subserve different functions during episodic retrieval. These functions are discussed in relation to a monitoring process, which operates when familiarity levels are close to response criterion and is associated with nonconfident judgements, and a recollective process, which is associated with the confident recognition of old words.

Memory orientation and success: separable neurocognitive components underlying episodic recognition

“…5) correlates with the degree to which subjects must closely monitor modest differences in item familiarity, an orientation that is particularly important when contextual recollection is unavailable or non-diagnostic. This interpretation is consistent with (a) demonstrations that involvement of right frontopolar and dorsolateral PFC during yes-no recognition appears to depend on the subject's expectancy regarding the ratio of old to new items on the test list [24], (b) neuropsychological evidence showing an inordinately high false recognition rate in a patient with right PFC damage [58,59], (c) ERP and fMRI evidence implicating right PFC with acontextual "know" and low confidence recognition responses [21,25,60], and (d) ERP data showing preferential involvement at electrodes over right PFC during discrimination following shallow compared to deep encoding [13].…”

“…In particular, we predicted that when the test required the recollection of contextual specifics regarding the encoding task, heightened activation would be observed in left prefrontal and lateral parietal cortices. However, when this information was rendered non-diagnostic and subjects were required to discriminate the recency of the items, right prefrontal regions implicated in familiarity monitoring were expected to be more active [14,21,25]. This latter prediction receives some support from two prior studies of recency recognition employing positron emission tomography [11,12].…”

“…Interestingly, the comparison of recency misses to recency hits yielded increased activation in right dorsolateral PFC and anterior cingulate (Table 3). Henson et al [25] suggested that right dorsolateral PFC is involved in monitoring processes that operate when familiarity values are close to the decision criterion. They reported activity in this region when contrasting low versus high confidence hits.…”

Prefrontal contributions to domain-general executive control processes during temporal context retrieval

“…Given that there were several cognitive control processes that were not directly manipulated in the current experiment, it is possible that right DLPFC activity in this study may be related to any of these control processes. However, our current results are consistent with previous studies implicating right DLPFC in monitoring processes engaged during familiarity-related retrieval processing (Dobbins, Simons, & Schacter, 2004;Dudukovic & Wagner, 2007;Henson, Rugg, Shallice, & Dolan, 2000;Petrides, 2000b) …”

“…The brain-behavior relationship reported by Fleck et al (2006) was domain-general, and since right BA 46/10 activity was not related to task RT (a continuous variable), but to response confidence (a categorical variable), the authors interpreted right BA 46/10 activity to be related to a discontinuous decision process such as selection of a response, as opposed to a retrievalrelated continuous process, such as post-retrieval monitoring. However, monitoring is a general cognitive process engaged when one evaluates his/her behavioral performance as being 'offtask' or not and may also be categorical since this process is more engaged under conditions of low confidence (Henson, Rugg, Shallice, & Dolan, 2000).…”