Knowing we know before we know: ERP correlates of initial feeling-of-knowing.

Task performance frequently involves selection among multiple strategies that could potentially lead to a correct response (Anderson & Lebiere, 1998; Reder, 1982; Reder, 1987; Siegler, 1996). People not only select among available strategies but also shift quickly and adaptively from one strategy to another depending on their cognitive abilities or features of the task environment (Lovett & Anderson, 1996; Reder, 1988; Reder & Ross, 1983; Reder, Wible, & Martin, 1986; Schunn & Reder, 2001; Schunn, Lovett & Reder, 2001). For people to select among strategies as quickly as they do, it is necessary that they possess heuristics that can be rapidly executed. Reder (1987) postulated that when deciding how to answer a question, people might use the familiarity of the question features to decide whether it is likely that the answer is known and that it is worthwhile to initiate a search of memory. Consistent with that conjecture, subjects were able to make a binary decision as to whether the answer to a general-knowledge question was likely to be known in considerably less time than they could begin articulating the answer itself, suggesting the heuristic could indeed influence the tendency to initiate a search (Reder, 1987).1 Although a generally good predictor of answer availability, the heuristic was shown to be imperfect and could be subverted by inducing spurious feelings of familiarity with pairs of terms in the question (Jameson, Narens, Goldfarb, & Nelson, 1990; Reder, 1987). Reder and Ritter (1992) conducted a further examination of the initial feeling-of-knowing (hereafter abbreviated FOK) heuristic in a task in which subjects were shown a series of unfamiliar math problems (e.g. 24 × 36), some of which were repeated many times over the course of the experiment. Subjects were required to respond in less than 850 ms whether or not they knew the answer. If “retrieve” was selected, the subject then had to quickly retrieve the answer. If “calculate” was selected, the subject had substantially longer to calculate the answer by hand. There was a monetary incentive to choose “retrieve,” but only if the correct answer could be given on time. Subjects performed this task with high accuracy. However, problems that looked similar but for which the answer was unknown resulted in spurious feelings-of-knowing. The conclusion of that study and a follow-up (Schunn, et al., 1997) is that people can rapidly assess whether they are likely to know the answer, but the assessment is not based on an early read of the answer. Instead, it is based on a partial match to the representation of a previously seen problem. The current study adopts the paradigm of Reder and Ritter (1992) while measuring ERPs to identify possible neural correlates of the initial FOK heuristic. We are unaware of any ERP studies on FOK. This paper should thus provide novel insight into the temporal dynamics of an important metacognitive process. Of particular interest is whether ERP components can be found that distinguish between the rapid strategy choice of whether to attempt to retrieve or rely on calculation, and if so, how early these components are observed following the appearance of the problem. If ERP correlates of FOK are found, they should signal a heuristic that is used to decide whether to search for the answer. We do not expect these ERP correlates to be a perfect predictor of whether the answer is known because the judgments themselves are imperfect. However, since we expect the FOK signal to be based on identification of familiar problems, the recognition memory literature should prove relevant. There is already an extensive literature on the ERP correlates of familiarity and recollection-based recognition, which can provide a useful guide as to how fast the FOK correlate could be expected to occur. The general consensus emerging from this literature is that familiarity-based processes are associated with frontal activity in the 300–500 ms time window, while recollection-based processes are associated with parietal activity in the 400–800 ms time window (Curran, 2000, 2004; see Rugg & Curran, 2007 for a review). Thus, if the FOK component emerges comparatively early (e.g. 300–500 ms), the result will provide evidence that initial FOK is indeed a familiarity-based effect. If, on the other hand, the FOK component is associated with late activation (emerging only after 400 ms), this would suggest reliance on a different mechanism, such as recollection of having seen the problem or partial retrieval of the answer. Our study should also prove relevant to research on conscious intentionality. There is evidence that there can be an appreciable delay before a stimulus enters conscious awareness (see Libet, 2003 for a review). One early study (Libet, Alberts, Wright, Lewis, & Feinstein, 1975) used a paradigm in which electrical stimulation of somatosensory cortex was followed by physical stimulation of the skin. The subject’s task was to decide which stimulus came first. Surprisingly, subjects reported that the skin stimulus occurred first even when it followed the cortex stimulation by up to 500 ms. This led to the conclusion that it takes several hundred ms for a stimulus to fully enter conscious awareness, at which time subjects backdate their estimate of when the stimulus occurred based on the onset of the early sensory components.2 More recent work has shown that seemingly “free” decisions by subjects can sometimes be predicted from brain activity occurring as much as 10 seconds before the decision enters awareness (Soon, Brass, Heinze, & Haynes, 2008). These studies are consistent with the view that unconscious processes play a critical role in rapid FOK judgments. Other research has also suggested that metacognitive processes need not rely on conscious awareness (Cary & Reder, 2002; Nhouyvanisvong & Reder, 1998; Reder, 1996; Reder & Schunn, 1996; Spehn & Reder, 2000). Finding a very early ERP correlate of FOK decisions would further support this position. Although we are aware that the ERP methodology contains inherent difficulties in localization, we believe there is still something to be gained by noting the approximate site where an ERP signal is strongest. Based on the available literature, we believe the most likely location from which an FOK correlate would emerge would be the frontal lobes, as there is extensive support in the literature for the idea that memory-monitoring processes in general are primarily dependent on this area (Fernandez-Duque, Baird, & Posner, 2000; Pannu & Kaszniak, 2005; Shimamura, 2000; Simons & Spiers, 2003). Studies of Alzheimer’s patients (Duke, 2001) and dysexecutive patients (Pinon, Allain, Zied Kefi, Dubas, & Le Gall, 2005), both of whom suffer primarily from damage to the frontal lobes, find that these patients are impaired (compared to healthy controls) in their ability to accurately predict whether they will later recognize an item that they have failed to retrieve. This provides further evidence for frontal involvement in metamemory. Thus, if it turns out that the ERP correlates of initial FOK (see footnote 1) suggest an origin in the frontal lobes, it would support the notion that the very rapid, initial FOK examined in this study relies on similar cognitive and neural processes as those used for other memory-monitoring tasks.