Subjective feelings of familiarity associated with a stimulus tend to be strongest when specific information about the previous encounter with the stimulus is difficult to retrieve . Recognizing: The judgment of previous occurrence. Psychological Review, 87, 252–271.]). When a stimulus has been encountered previously and the circumstances of the encounter cannot be recollected, additional cognitive resources may be directed toward recollection processes; this resource allocation is accompanied by autonomic arousal [Dawson, M. E., Filion, D. L., & Schell, A. M. . (...) Is elicitation of the autonomic orienting response associated with allocation of processing resources?. Psychophysiology, 26, 560–572]. One easily measurable index of autonomic arousal is the skin conductance response . In the present study, participants studied lists of words and then gave recognition ratings to briefly displayed and masked studied and nonstudied test words while their SCRs were monitored. Results revealed a relationship between recognition ratings and the temporal characteristics of the SCR, supporting the idea that feelings of familiarity are indeed “feelings” in that they stem from autonomic arousal associated with cognitive resource allocation. (shrink)

Déjà vu is the striking sense that the present situation feels familiar, alongside the realization that it has to be new. According to the Gestalt familiarity hypothesis, déjà vu results when the configuration of elements within a scene maps onto a configuration previously seen, but the previous scene fails to come to mind. We examined this using virtual reality technology. When a new immersive VR scene resembled a previously-viewed scene in its configuration but people failed to recall the previously-viewed scene, (...) familiarity ratings and reports of déjà vu were indeed higher than for completely novel scenes. People also exhibited the contrasting sense of newness and of familiarity that is characteristic of déjà vu. Familiarity ratings and déjà vu reports among scenes recognized as new increased with increasing feature-match of a scene to one stored in memory, suggesting that feature-matching can produce familiarity and déjà vu when recall fails. (shrink)

A central feature of our waking mental experience is that our attention naturally toggles back and forth between “external” and “internal” stimuli. In the midst of an externally demanding task, attention can involuntarily shift internally with no clear reason how or why thoughts momentarily shifted inward. In the case of external attention, we are typically exploring and encoding aspects of our external world, whereas internal attention often involves searching for and retrieving potentially relevant information from our memory networks. Cognitive science (...) has traditionally focused on understanding forms of internal and external attention separately, leaving a mystery about what sparks the seemingly automatic shifts between the two. Specifically, what shifts attentional focus from being outward‐directed to being inward‐directed? We present a candidate mechanism: Familiarity‐detection. (shrink)

We propose that IAM and déjà vu may not share a placement on the same gradient, per se, but the mechanism of cue familiarity detection, and a major differentiating factor between the two metacognitive experiences is whether the resulting inward directed search of memory yields retrieved content or not. Déjà vu may manifest when contentless familiarity detection is inexplicable by the experiencer.