Sustained conscious access to incidental memories in RSVP

Abstract

In visual search of natural scenes, differentiation of briefly fixated but task-irrelevant distractor items from incidental memory is often comparable to explicit memorization. However, many characteristics of incidental memory remain unclear, including the capacity for its conscious retrieval. Here, we examined incidental memory for faces in either upright or inverted orientation using Rapid Serial Visual Presentation (RSVP). Subjects were instructed to detect a target face in a sequence of 8-15 faces cropped from natural scene photographs (Experiment 1). If the target face was identified within a brief time window, the subject proceeded to an incidental memory task. Here, subjects used incidental memory to discriminate between a probe face (a distractor in the RSVP stream) and a novel, foil face. In Experiment 2 we reduced scene-related semantic coherency by intermixing faces from multiple scenes and contrasted incidental memory with explicit memory; a condition where subjects actively memorised each face from the sequence without searching for a target. In both experiments, we measured objective performance (Type 1 AUC) and metacognitive accuracy (Type 2 AUC) revealing sustained and consciously accessible incidental memory for upright and inverted faces. In novel analyses of face categories, we examined whether accuracy or metacognitive judgements are affected by shared semantic features (i.e., similarity in gender, race, age). Similarity enhanced the accuracy of incidental memory discriminations but did not influence metacognition. We conclude that incidental memory is sustained and consciously accessible, is not reliant on scene contexts, and not enhanced by explicit memorization.

Conscious access in the near absence of attention: critical extensions on the dual-task paradigm

“…The most important of these was metacognition: whether successful discrimination of faces in the near absence of top-down attentional amplification is achieved with conscious access. We assessed this by computing metacognitive accuracy, the correspondence between subjects' accuracy and subjective reports [54,55,57,61,65,66]. Metacognitive accuracy under the dual task has rarely been investigated (but see [56,67]).…”

“…We assessed the correspondence between subjects' discrimination accuracy and subjective reports of either confidence (experiments 1 and 2) or perceptual awareness (PAS, experiment 3) using type 2 AUC [54,57,61,66,68]. For gender discrimination, objective performance, confidence ratings and metacognitive accuracy did not differ greatly between the single (i.e.…”

“…A set of 65 male and 65 female faces were selected from natural crowd scenes, details of which are described elsewhere [57,61]. All were facing forward with major features (i.e.…”

“…In addition to objective and subjective signal detection metrics to measure performance, we employed linear mixed effects (LME) modelling to examine metacognitive accuracy [57]. We also examined trade-off in performance between (e) QUEST staircase procedure and reduced training Previous dual-task studies employed large amounts of training to stabilize subjects' performance at the threshold SOAs [19,23 -25].…”

“…Third, we accounted for faces attracting bottom-up spatial attention by blending face and disc stimuli through transparency (alpha (a) blending) and examining whether the colour orientation of the disc is reportable when the stimuli are co-located. Fourth, we directly assessed metacognitive insight for unattended peripheral stimuli, a signifier of conscious access, by quantifying trial-by-trial confidence ratings and perceptual awareness judgements as a function of task accuracy [54][55][56][57]. With these improvements over previous approaches, we critically assessed the necessity of top-down attention for conscious access of stimuli with high and low complexity.…”