The Solution to the Surprise Exam Paradox

The Surprise Exam Paradox continues to perplex and torment despite the many solutions that have been offered. This paper proposes to end the intrigue once and for all by refuting one of the central pillars of the Surprise Exam Paradox, the “No Friday Argument,” which concludes that an exam given on the last day of the testing period cannot be a surprise. This refutation consists of three arguments, all of which are borrowed from the literature: the “Unprojectible Announcement Argument,” the “Wright & Sudbury Argument,” and the “Epistemic Blindspot Argument.” The reason that the Surprise Exam Paradox has persisted this long is not because any of these arguments is problematic. On the contrary, each of them is correct. The reason that it has persisted so long is because each argument is only part of the solution. The correct solution requires all three of them to be combined together. Once they are, we may see exactly why the No Friday Argument fails and therefore why we have a solution to the Surprise Exam Paradox that should stick.     

What makes recognition without awareness appear to be elusive? Strategic factors that influence the accuracy of guesses

Various factors could conceivably promote the accuracy of guesses during a recognition test. Two that we identified in previous studies are forced-choice testing format and high perceptual similarity between the repeat target and novel foil. In restricted circumstances, the relative perceptual fluency of the target can be compared with that of the foil and used as a reliable cue to guide accurate responses that occur without explicit retrieval—a phenomenon we referred to as “implicit recognition.” In this issue, Jeneson and colleagues report a failure to replicate accurate guesses and also a tendency on the part of subjects to hazard guesses infrequently, even though testing circumstances were very similar to those that we used. To resolve this discrepancy, we developed a simple manipulation to encourage either guessing or confident responding. Encouraging guessing increased both the prevalence of guesses and the accuracy of guesses in a recognition test, relative to when confident responding was encouraged. When guessing was encouraged, guesses were highly accurate (as in our previous demonstrations of implicit recognition), whereas when confident responding was encouraged, guesses were at chance levels (as in Jeneson and colleagues'' data). In light of a substantial literature showing high accuracy despite low confidence in certain circumstances, we infer that both the prevalence and accuracy of guessing can be influenced by whether subjects adopt guessing-friendly strategies. Our findings thus help to further characterize conditions likely to promote implicit recognition based on perceptual fluency.In several prior experiments, we reported findings indicative of recognition without awareness (Voss et al. 2008; Voss and Paller 2009). The experiments involved recognition tests for colorful and complex geometric shapes (kaleidoscope images). Subjects attempted to discriminate repeat stimuli (targets) from novel stimuli (foils). In some of our experiments, subjects made recognition responses and also rated the quality of their recognition experience or their confidence in their decision. For example, recognition often occurred with awareness of memory retrieval and with some level of confidence. On the other hand, correct recognition of a target sometimes occurred with no discernable awareness of memory retrieval or confidence; essentially, subjects felt that their response was merely a guess—and yet they were correct.Of course, the reason that a guess might be correct in a recognition test might have nothing at all to do with the subject having retrieved relevant information; the response might be merely a “lucky guess.” Our results, however, provided evidence that processes of implicit memory were operative in producing at least a subset of the correct guesses. In recognition tests using a forced-choice format, targets and foils shared a high degree of perceptual similarity and were displayed side-by-side, and we found that, for guess responses, the repeat stimulus was correctly selected remarkably often. With no stored information (and given that the target occurred equally often on the left side and the right side, and that targets and foils were counterbalanced across subjects), the repeat stimulus should be selected correctly 50% of the time in the long run. In our original report, we found that 82% of the guess responses were correct, which was more accurate than responses when trials with high- or low-confidence responses were pooled together (56%; data combined for all study conditions) (Experiment 2 of Voss et al. 2008). We referred to this phenomenon as recognition without awareness or implicit recognition. For the present discussion, we will use the latter term.Indeed, our results provided several additional reasons for linking implicit memory with this phenomenon of implicit recognition. In one experiment, each trial was classified as either (1) a recognition experience in which subjects recollected episodic information from their initial experience with the target; (2) recognition with familiarity for the target, but no other recall of prior information concerning the target; or (3) a guess with no confidence in the accuracy of the response (Voss and Paller 2009). We found that guesses were approximately as accurate as recollection responses (73% vs. 79%, respectively, averaged across encoding conditions), and that guesses were more accurate than decisions based on familiarity (59%, averaged across encoding conditions).Another feature of these experiments was that we contrasted two types of learning conditions. In one condition, to-be-remembered stimuli were viewed while subjects simultaneously performed a verbal working memory task. This task required that the subject listen to a spoken digit on each trial and respond according to whether the digit on the prior trial was odd or even (i.e., a one-back task). In the other condition, there were no spoken digits, and attention could be allocated fully to viewing the to-be-remembered stimuli. In several different experiments, recognition accuracy was higher with divided-attention study than with full-attention study. Although this is a highly unusual outcome for recognition performance, it was clear that divided attention during the study led to relatively less confidence during the recognition test, such that guessing was more prevalent, and these guess responses were highly accurate.Notably, these two key results—highly accurate guessing, and a recognition advantage for divided over full attention at study—were not obtained when recognition was tested with a yes–no format (targets and highly similar foils randomly intermixed and shown one stimulus at a time), or when a forced-choice test was prepared such that each target was paired with a random foil rather than a highly similar foil (Voss et al. 2008). On the basis of these findings, as well as additional results from electrophysiological recordings (described below in the Discussion section), we argued that subjects were able to weigh the relative perceptual fluency of the target and the foil only for forced-choice tests with high target/foil similarity, and then they could use this fluency cue to guide accurate selection of the target (Voss and Paller 2009).We aim to develop a line of reasoning to clarify why implicit recognition might tend to operate preferentially in certain circumstances, such as when the relative perceptual fluency of targets versus foils is likely to serve as a useful cue, and when the ability to remember specific stimulus details does not provide a useful cue (as is the case when these details are largely shared between the target and the foil). In many situations, however, perceptual fluency may not be a good basis for making recognition judgments. Often, accurate recognition reflects conceptual elaboration about the meaning of an event, and the conceptual features are typically remembered more robustly than the set of stimulus features perceived during the course of the event. Thus, implicit recognition may be less likely to guide a response in a recognition test in the presence of confident memory for the target. Dividing attention during encoding resulted in lower confidence during the recognition test, and this may have been one factor that promoted reliance on signals of relative perceptual fluency. Of course, there may be other factors that also promote or inhibit this type of strategy in a recognition test.     

Bootstrapping and Content Parts

Christensen [Philosophy of Science, 50: 471–481, 1983] and [Philosophy of Science, 57: 644–662, 1990] provides two sets of counter-examples to the versions of bootstrap confirmation for standard first-order languages presented in Glymour [Theory and Evidence, Princeton University Press, Princeton, 1980] and [Philosophy of Science, 50: 626–629, 1983]. This paper responds to the counter-examples of Christensen [Philosophy of Science, 50: 471–481, 1983] by utilizing a new notion of content introduced in Gemes [Journal of Philosophical Logic, 26, 449–476, 1997]. It is claimed that this response is better motivated and more effective than that presented in Glymour [Philosophy of Science, 50: 626–629, 1983]. It is then argued that while this response meets some of the counter-examples of Christensen [Philosophy of Science, 57: 644–662, 1990] two of those counter-examples, though not unanswerable, suggest the need for a substantial reformulation of the formal versions of bootstrapping. The essay proceeds with such a reformulation, arguing that this new formulation better fits the philosophical insights that originally motivated bootstrapping than do Glymour’s earlier formulations. In the concluding sections some alternative solutions to the problem posed by the Christensen counter-examples are discussed.     

Why Do People Engage in Collective Action? Revisiting the Role of Perceived Effectiveness

Research has shown limited support for the notion that perceived effectiveness of collective action is a predictor of intentions to engage in collective action. One reason may be that effectiveness has been in terms of whether the action will influence key decision makers. We argue that the effectiveness of collective action might be judged by other criteria, such as whether it influences third parties, builds an oppositional movement, and expresses values. Two hundred and thirty one attendees at a rally rated the effectiveness of the rally and their intentions to engage in future collective action. For those participants who were not members of an organization, intentions were linked to the perceived effectiveness of the rally in expressing values and influencing the public. For those who were members of an organization, intentions were linked only to the effectiveness of the rally in building an oppositional movement.     

Assessing Alexithymia: Psychometric Properties and Factorial Invariance of the 20-Item Toronto Alexithymia Scale in Nonclinical and Psychiatric Samples

The 20-item Toronto Alexithymia Scale (TAS-20) is a self-report questionnaire designed to measure the three components of alexithymia; difficulty identifying feelings in the self (DIF), difficulty describing feelings (DDF), and externally orientated thinking (EOT). We examined the scale’s psychometric properties in Australian nonclinical (N = 428) and psychiatric (N = 156) samples. In terms of factorial validity, confirmatory factor analyses found the traditional 3-factor correlated model (DIF, DDF, EOT) to be the best and most parsimonious solution, but it did not reach adequate levels of goodness-of-fit in either sample. Several EOT items loaded poorly on their intended factor, and a reverse-scored item method factor was present; the factor structure of the scale was invariant across both samples. A higher-order factor model (with a single higher-order factor) was slightly inferior to the correlated models, but still tenable. The total scale score and DIF and DDF subscales displayed sound internal consistency, but the EOT subscale did not. We conclude that the TAS-20 has, for the most part, adequate psychometric properties, though interpretation should focus only on the total scale score and DIF and DDF subscales; we recommend the EOT subscale score not be used. Implications for clinical use and future revision of the scale are discussed.