The article reports 4 experiments that explore the notion of recognition without awareness using words as the material. Previous work by Voss and associates has shown that complex visual patterns were correctly selected as targets in a 2-alternative forced-choice (2-AFC) recognition test although partici- pants reported that they were guessing. The present experiments sought to extend this earlier work by having participants study words in different ways and then attempt to recognize the words later in a series of 4-alternative forced-choice (4-AFC) tests, some of which contained no target word. The data of interest are cases in which a target was present and participants stated that they were guessing, yet chose the correct item. This value was greater than p = .25 in all conditions of the 4 experiments, demonstrating the phenomenon of recognition without awareness. Whereas Voss and colleagues attributed their findings with kaleidoscope patterns to enhanced processing fluency of perceptual attributes, the main factor associated with different levels of recognition without awareness in the present studies was a variable criterion for the subjective state accompanying selection of the “guess” option, depending on the overall difficulty of the recognition test. We conclude by discussing some implications of the results for the distinction between implicit and explicit memory.
Keywords: recognition, awareness, criterion shifts, implicit memory, explicit memory
In real-life decision situations, we are often faced with alternatives that seem so equivalent that choice is extremely difficult. Under such circumstances our final selection may feel like an arbitrary choice, although in fact there may be implicit influences acting outside conscious control that bias us toward selecting one alternative over another. The observation that people can make correct choices while believing that they are selecting randomly has a long history in experimental psychology. Studies dating from the 19th century have consistently found that participants can make subtle perceptual discrimination judgments with above- chance accuracy despite claims that they are simply guessing (Adams, 1957; Voss & Paller, 2010). Voss and colleagues have recently provided evidence for a similar effect in recognition memory (Voss, Baym & Paller, 2008). Participants studied a series of kaleidoscope images and then attempted to recognize the stud- ied items among a set of perceptually similar pairs.
This article was published Online First May 25, 2015.
Fergus I. M. Craik, Nathan S. Rose, and Nigel Gopie, Rotman Research Institute at Baycrest, Toronto, Ontario, Canada.
Nathan S. Rose is now at the School of Psychology, Australian Catholic University. Nigel Gopie now works for IBM, Global Business Services, New York, NY.
This work was supported by a research grant from the Natural Sciences and Engineering Research Council of Canada to Fergus Craik (Grant A8261). We thank Karen Lau for assistance in preparing and conducting the experiments, and Ellen Bialystok for helpful comments on the exper- iments and on the manuscript. We also thank Murray Singer for drawing our attention to the criterion shift account, and reviewers of a previous version for their helpful remarks.
phase was performed under either full attention (FA) or divided attention (DA) conditions, and the recognition test was either a yes-no test (10 studied targets mixed with 10 similar foils) or a 2-AFC test (10 simultaneously presented target-foil pairs). In the yes-no test, recognition accuracy was good following encoding under FA conditions but very poor following DA at encoding, as one might expect in an explicit memory situation. Surprisingly, however, participants’ performance on the forced-choice test was better following DA than FA at encoding. Further experiments revealed that when participants were asked to rate their forced- choice responses as being on the basis of some memory for the studied item or as random guesses, recognition accuracy was higher for responses judged to be guesses than for those thought to be based on memory.
These experiments thus provide evidence for substantial levels of recognition memory when participants believe they are simply guessing—that is, for recognition without awareness. This result was obtained only under very specific conditions, however—when encoding was performed under DA conditions, when the test was 2-AFC, when responding was under a tight time deadline (c. 2 sec from stimulus onset), and when the choice was between two perceptually similar visual patterns. There was essentially no ev- idence for the effect with a yes-no testing procedure or even with a forced-choice procedure when participants were given unlimited time to respond or when target stimuli were paired with a percep- tually dissimilar foil (Voss et al., 2008, Experiments 3 & 4, respectively). A subsequent study revealed a further limitation; the effect was not obtained in the forced-choice procedure when participants were encouraged to respond accurately and guess only when absolutely necessary, although the original result reappeared when participants were encouraged to guess (Voss & Paller, 2010). Voss and colleagues refer to their finding as “implicit recogni- tion” and suggest that the underlying processes are different both from those mediating explicit recollection and from those medi- ating feelings of familiarity. They comment that “Familiarity- based recognition is taken as an instance of explicit memory because familiarity responses entail the awareness of memory retrieval” (Voss et al., 2008, p. 458). In support of the claim that implicit recognition has a different mechanism they cite a further study (Voss & Paller, 2009) in which participants performed the forced-choice test for kaleidoscope patterns, encoded under either FA or DA conditions. Participants in this study assessed each recognition choice as being associated with some explicit recol- lection of the encoding phase (“remember” = R), with a more general feeling of familiarity (they simply “knew” it had been studied = K), or as a pure guess. Event-related potential (ERP) recordings were also made during the recognition test. The results confirmed earlier findings of higher levels of accuracy following DA at encoding, and also of greater than chance accuracy levels with “guess” responses, especially in the DA condition. Addition- ally, the pattern of behavioral results in guess decisions was distinct from the pattern observed with both R and K decisions, suggesting that the mechanism associated with implicit recognition is different from that associated with recognition with awareness. The ERP results supported this claim. Recognition responses ac- companied by feelings of recollection or familiarity were associ- ated with positive shifts in the late positive complex (600 –900 ms) and in the P200 potential. In contrast, correct guess responses were associated with frontal-occipital negative potentials occurring 200 – 400 ms after stimulus onset. The authors speculate that the distinct mechanism underlying the phenomenon of recognition without awareness may reflect a stimulus-specific enhancement of perceptual fluency (e.g., Jacoby & Whitehouse, 1989), with this subtle change in processing yielding enough information to sup- port a correct recognition choice, although not enough to give rise to any conscious feeling of remembering.
A major question arising from this work is whether the phe- nomenon of recognition without awareness can be demonstrated with material other than complex perceptual patterns and, if so, whether it is associated with similar neural mechanisms. Is implicit recognition found with verbal materials, for example? In one early experiment, Peynirciog˘lu (1990) had participants study a list of words, and then gave them a word-fragment completion test in which some fragments were from the list and others were new. Participants attempted to complete the fragments and also rated each fragment with regard to whether it was based on a list member or based on a new word. Considering only fragments that were not completed, a higher mean rating was given to list than lure words. Thus, apparently participants had some sense of fa- miliarity for the fragments even in the absence of identification. Subsequent work by Cleary and Greene (2004, 2005) showed that when studied and unstudied words were presented too quickly to identify in a perceptual identification test, participants could still discriminate studied from unstudied items. The authors attributed the effect to a greater sense of familiarity associated with the briefly flashed studied words. The finding that recognition without identification is associated with a specific ERP signal (Voss & Paller, 2009) was confirmed and extended to verbal material in a study using the method of Peynirciog˘lu (1990) and reported by Ryals, Yadon, Nomi, and Cleary (2011). The two major findings were, first, that for unidentified word fragments the proportion attributed to the original list was greater for studied than unstudied
unidentified items; that is, recognition without identification (RWI) was again obtained. Second, the ERP correlate of the RWI effect was an N300 component of the evoked response, in agree- ment with Voss and Paller (2009) but using verbal materials and a yes-no recognition procedure. Ryals and colleagues concluded that their results confirmed the existence of unconscious recognition memory and that the RWI effect is indexed by the N300 ERP signature.
A study by Starns, Hicks, Brown, and Martin (2008) also found evidence for recognition without identification using verbal mate- rial. Their basic paradigm was to have participants study a list of words in which half of the words were printed in large font and half in small font (Experiment 1), or were rated for either pleas- antness or imageability (Experiments 2 & 3). Participants were then given a recognition list composed of 50% studied words and 50% lures; additionally, half of the participants were informed that only 25% were targets and the other half informed that 75% were targets. Following this test, participants were re-presented with the original list and asked to decide the “source”—that is, whether each word had been in small or large font (or rated for pleasantness or imageability). The major finding was that participants’ source judgments were above chance for words they had failed to recog- nize in the first test. Importantly, however, this effect was found only in the condition in which participants were informed that only 25% of the test words were targets. The authors concluded that the phenomenon of accurate source memory for unrecognized items is a reality, but that it occurs only under conditions in which a conservative response bias has been induced.
In summary, there is good evidence for the phenomenon of recognition without awareness, although the evidence associated with verbal materials is somewhat indirect in the sense that correct decisions about list membership were made on the basis of word fragments or the words themselves presented very briefly (Cleary and colleagues). Similarly, in the experiments by Starns et al. (2008) the evidence for recognition without identification comes from above-chance attribution of source rather than of the words themselves. One interesting question then is whether the phenom- enon would extend to conditions in which participants correctly select words presented in full view despite claiming that they are simply guessing. This is the question addressed in the present experiments.
We became interested in these findings when considering the results of an earlier set of experiments reported by Gopie, Craik and Hasher (2011). In that study, younger and older adult partic- ipants first named the print color (red, green, blue, yellow) of a series of words as rapidly as possible; they were informed that the words themselves were irrelevant. This encoding phase was fol- lowed by a word fragment completion test, containing fragments of words from the “encoded” list as well as new word fragments. The higher completion rate for repeated words than for new words (priming effect) was greater for older adults (0.25) than for younger adults (0.10), in line with the notion that older adults fail to inhibit “irrelevant” information, which they can subsequently use if that information becomes useful (Hasher, Zacks & May, 1999). Surprisingly, however, this pattern reversed in a second experiment using the same color-naming initial phase, but with explicit instructions to “use words from the initial list where possible” in the fragment-completion test. Now younger adults had a priming score of 0.24 and older adults’ score dropped to 0.08.
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