Adult subjects were presented with two auditory stimuli per trial, and their task was to decide which ofthe two was longer in duration. An adaptive psychophysical procedure was used. In Experiments 1, 2, and 4, the base duration was 50 msec, whereas in Experiment 3, the base duration was 1 sec. In Experiments 1,2, and 4, it was found that filled intervals (continuous tones) were discriminated more accurately than empty intervals (with onset and offset marked by clicks). It was concluded that this difference was perceptual rather than cognitive in nature, since performance on filled and empty intervals was not affected by increasing cognitive load in a dual-task procedure (Experiment 2) but was affected by backward masking (Experiment 4). In contrast, the results of Experiment 3 showed that duration discrimination of filled auditory intervals oflonger duration was cognitively influenced, since performance was impaired by increasing cognitive load. Implications for notions of perceptual processing and timing mechanisms underlying differences in duration discrimination with filled and empty intervals are discussed.There are two types of stimuli used in time perception studies. One type is the empty (silent) interval and the other type is the filled interval. In auditorily marked empty intervals, for example, only the onset and the offset of the interval are marked by clicks, whereas in filled intervals, a tone or noise burst is presented continuously throughout the interval. Thus, in empty intervals, there is no auditory stimulus presented during the interval itself. Surprisingly, there are very few published studies on the influence of filled versus empty intervals on performance in time perception experiments involving brief intervals (i.e., intervals less than 1 sec in duration).In her review article, Allan (1979) suggested that given the results of two duration-discrimination studies reported by Abel (1972aAbel ( , 1972b, one can conclude that performance with filled intervals appears to be more accurate than performance with empty intervals. However, this comparison was not the focus of Abel's studies. In a study by Craig (1973), subjects had to adjust the time between two lOOO-Hz tones until it appeared equal in duration to the first tone. Craig found a constant error in the percepPortions of this research were presented at the annual convention of the American Psychological Association, in San Francisco, August 1991. Preparation of this article was supported by NIH Grant AG09130-01 to Susan O. Lima. We thank Lester Krueger, Lorraine Allan, and Lloyd Avant for helpful comments. Correspondence may be addressed to Thomas H. Rammsayer, Department of Psychology, University of Giessen, Otto-Behaghel Str. lOF, 0-6300 Giessen, Germany (e-mail: Thoram@DGIHRZOI.bitnet).tion of empty intervals relative to filled intervals. This finding joins those of Abel (1972aAbel ( , 1972b in suggesting that performance on filled intervals is more accurate than performance on empty intervals. Although Craig concluded that different ...

Three analyses are reported that are based on data from 19 studies using lexical tasks and a reduced version of the Hale, Myerson, and Wagstaff (1987) nonlexical data set. The results of Analysis 1 revealed that a linear function with a slope of approximately 1.5 described the relationship between the lexical decision latencies of older (65-75 years) and younger (19-29 years) adults. The results of Analysis 2, based on response latencies from 6 lexical tasks other than lexical decision, revealed a virtually identical linear relationship. In Analysis 3, it was found that performance on nonlexical tasks spanning the same range of task difficulty was described by a significantly steeper regression line with a slope of approximately 2.0. These findings suggest that although general cognitive slowing is observed in both domains, the degree of slowing is significantly greater in the nonlexical domain than in the lexical domain. In addition, these analyses demonstrate how the meta-analytic approach may be used to determine the limits to the external validity of experimental findings.

Two experiments tested the hypothesis that lexical access in reading is initiated on the basis of word-initial letter information obtainable in the parafoveal region. Eye movements were monitored while college students read sentences containing target words whose initial trigram (Experiment 1) or bigram (Experiment 2) imposed either a high or a low degree of constraint in the lexicon. In contradiction to our hypothesis, high-constraint words (e.g., DWARF) received longer fixations than did low-constraint words (e.g., CLOWN), despite the fact that high-constraint words have an initial letter sequence shared by few other words in the lexicon. Moreover, a comparison of fixation times in viewing conditions with and without parafoveal letter information showed that the amount of decrease in target fixation time due to prior parafoveal availability was the same for high-constraint and low-constraint targets. We concluded that increased familiarity of word-initial letter sequence is beneficial to lexical access and that familiarity affects the efficiency of foveal but not parafoveal processing.

Milwaukee Analyses of lexical decision studies revealed that (a) older (O) adults' mean semantic priming effect was 1.44 times that of younger (Y) adults, (b) regression lines describing the relations between older and younger adults' latencies in related (O = 1.54 Y-112) and unrelated conditions (O = 1.50 Y-93) were not significantly different, and (c) that there was a proportional relation between older and younger adults' priming effects (O = 1.48 Y-2). Analyses of word-naming studies yielded similar results. Analyses of delayed pronunciation data (Balota & Duchek, 1988) revealed that word recognition was 1.47 times slower in older adults, whereas older adults' output processes were only 1.26 times slower. Overall, analyses of whole latencies and durations of component processes provide converging evidence for a general slowing factor of approximately 1.5 for lexical information processing.

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