No abstract

This paper describes new methods for fast correlation attacks, based on the theory of convolutional codes. They can be applied to arbitrary LFSR feedback polynomials, in opposite to the previous methods, which mainly focus on feedback polynomials of low weight. The results improve significantly the few previous results for this general case, and are in many cases comparable with corresponding results for low weight feedback polynomials.

No abstract

Working memory for odors, which has received almost no attention in the literature, was investigated in two experiments. We show that performance in a 2-back task with odor stimuli is well above chance. This is true not only for highly familiar odors, as has been shown by Dade, Zatorre, Evans, and Jones-Gotman, NeuroImage, 14, 650-660, (2001), but also for unfamiliar ones that are notoriously difficult to name. We can conclude that information about an olfactory stimulus can be retained in the short term and can continuously be updated for comparison with new olfactory probes along the lines of a functional odor working memory. However, the performance in the working memory task is highly dependent on participants' verbalization of the odor. In addition, results indicated that odor working memory performance is dependent on the ability to discriminate among the odor stimuli (Experiment 2). The results are discussed in relation to recent ideas of a separate olfactory working memory slave system.

Abstract. The task of a fast correlation attack is to efficiently restore the initial content of a linear feedback shift register in a stream cipher using a detected correlation with the output sequence. We show that by modeling this problem as the problem of learning a binary linear multivariate polynomial, algorithms for polynomial reconstruction with queries can be modified through some general techniques used in fast correlation attacks. The result is a new and efficient way of performing fast correlation attacks.

A metacognitive perspective is utilized to elucidate why it is so difficult to name common odors and what characterizes the subjective knowledge people have about their actual odor knowledge. Odor-naming failures are often accompanied by strong feelings of knowing (FOK) or feelings of imminent retrieval of what it is that smells. The paper's two experiments investigate FOK judgements and tip of the tongue (TOT) experiences for odor and person names. The data indicate that our inability to correctly name odors are typically not due to the often proposed uniquely poor association between odors and their proper names, but rather due to failures to identify the odors, that is, failures to know 'what it is'. It was also found that (i) TOT experiences are very unusual for odor names and more so than for person names; (ii) FOK judgements about odor names are significantly less predictive of later retrieval than equivalent judgements about names of persons; (iii) FOK judgements were highly correlated with the familiarity of the cue (odor or picture of famous person), rendering some support for the idea that FOK judgements are based on the perceived familiarity of the cue triggering the FOK; and (iv) the idea that FOK judgements are based on the amount of available information about the sought-for memory (accessibility theory) was also supported.

Previous research has demonstrated that participants are overconfident in the veracity of their odor identifications. This means that their confidence expressed as subjective probabilities is, on average, higher than the actual proportion of correct odor identifications. The current experiment tested the hypothesis that the more arousing an odor is, the more participants are overconfident in their identification of it. The results indicated that part of the overconfidence in odor identification can, indeed, be due to the arousing properties of the odors. This suggests that emotional variables should be taken into account when researching metamemory.

Combining study and test trials during learning is more beneficial for long-term retention than repeated study without testing (i.e., the testing effect). Less is known about the relative efficacy of different response formats during testing. We tested the hypothesis that overt testing (typing responses on a keyboard) during a practice phase benefits later memory more than covert testing (only pressing a button to indicate successful retrieval). In Experiment 1, three groups learned 40 word pairs either by repeatedly studying them, by studying and overtly testing them, or by studying and covertly testing them. In Experiment 2, only the two testing conditions were manipulated in a within-subjects design. In both experiments, participants received cued recall tests after a short (~19 min) and a long (1 week) retention interval. In Experiment 1, all groups performed equally well at the short retention interval. The overt testing group reliably outperformed the repeated study group after 1 week, whereas the covert testing group performed insignificantly different from both these groups. Hence, the testing effect was demonstrated for overt, but failed to show for covert testing. In Experiment 2, overtly tested items were better and more quickly retrieved than those covertly tested. Further, this does not seem to be due to any differences in retrieval effort during learning. To conclude, overt testing was more beneficial for later retention than covert testing, but the effect size was small. Possible explanations are discussed.