Duration judgment and the experience of change

W. DOUGLAS POYNTER 0 DONALD HOMA 0 0 Arizona State University , Tempe, Arizona Predictions based on storage size, processing effort, and change models of time estimation were tested in five experiments. The first of these presented subjects with stimulus patterns that varied on dimensions of sensory-event number and uncertainty. Subjects estimated the duration of time periods using the reproduction method. Duration estimates were most accurately predicted by the number of sensory events in each pattern. This relationship was generally positive, although the specific function relating these variables was dependent upon clock duration. The change model seemed to fit these data best. Experiment 2 demonstrated that the relationship between sensory change and judged duration was not due to the total time of sensory input. Experiments 3, 4, and 5 tested the effects of several different types of change. In Experiments 3 and 4, the number C1f sensory events was held constant, but the regularity of their spatial presentation was varied. In both experiments, duration judgments were positively related to the number of changes that occurred. Because the manipulations used in these experiments produced differences in the visual complexity of stimulus patterns, the argument could be made that storage size or processing effort accounted for the size of duration judgments. Experiment 5 tested the effects of change while holding the visual complexity of stimulus patterns constant. A positive relationship between duration judgments and number of changes was again found. - Given the ubiquity of man-made clocks in modern societies, it seems clear that humans frequently rely on nonorganismic mechanisms to measure the tem poral extent of events. Apart from these time keeping devices, however, we still experience some thing metaphorically referred to as "time passage," and can also generate estimates of duration using organismic processes. Although time perception has been the topic of scientific investigation for at least 90 years, a clear understanding of the psychological mechanisms of duration estimation is still forth coming. Some of the earliest researchers proposed that the experience of duration was based on the out put of a biological clock (e.g., Francois, 1927; Hoagland, 1933). Recent models have emphasized the role of cognitive activity rather than metabolic functioning. This cognitive approach has the ad vantage of being able to explain why the quantity of stimulus information in an interval of clock time can affect its apparent duration. When increases The manuscript is based on the first author's doctoral disser tation. Reprint requests should be addressed to W. Douglas Poynter, Department of Psychology, Arizona State University, Tempe, Arizona 85287. The authors would like to acknowledge the valuable contributions made by Jerry Kosisky in the per formance of the experiments. They also thank Sam Leifheit and Norwood Sisson for their major contributions to the con struction of the apparatus. Pat Query's patience in typing the manuscript is also greatly appreciated. Finally, comments on the manuscript by Richard Block, Dominic W. Massaro, and an anonymous reviewer were helpful and much appreciated. in stimulus information produce longer estimates of duration, this finding is sometimes referred to as the filled-duration illusion (FOI) and has been demonstrated with an impressive variety of inter val "fillers," including light flashes (Buffardi, 1971), pure tone bursts (Adams, 1977; Buffardi, 1971; Thomas & Weaver, 1975), line drawings (Mulligan & Schiffman, 1979; Ornstein, 1969), letters and non sense syllables (Avant, Lyman, & Antes, 1975), and words and word lists (Block, 1974; Poynter, 1979; Thomas & Weaver, 1975). Generally, manipulations of the content of time intervals fall into three categories: (1) manipulations of the number of intervening events (Adams, 1977; Block, 1974; Buffardi, 1971), (2) manipulations of the complexity of stimulus events (Block, 1978; Ornstein, 1969; Schiffman and Bobko, 1974), and (3) manipulations of the amount or type of infor mation processing required of subjects (Burnside, 1971; Hicks, Miller, & Kinsbourne, 1976; Thomas & Weaver, 1975). Based on the outcome of experiments using three basic categories of experimental manipulation, three cognitive models have been developed. These will be referred to as the storage size, processing effort, and change models. ~ They are similar in assuming a close relationship between duration judgment and the processing of interval events; they differ in terms of the particular dimension of processing that is proposed to mediate duration experience. The storage-size notion proposes that time estimates are based on both the number and complexity of stimulus representations in memory; the processing effort model focuses on the processing time or at tention requuired by interval events; and the change model emphasizes the overall amount of change ex perienced. The results of many experiments can be interpreted from more than one of these three perspectives, although data have usually been dis cussed in relation to a single model. The next section presents evidence in support of each model. Models of Duration Judgment Storage size model. Experiments that have tested this hypothesis often manipulate the number or memorability of items filling an interval and relate subsequent recall or recognition of these items to duration estimates. Block (1974), for example, pre sented subjects with 16O-sec intervals filled with 80 categorized words either blocked by category or presented in random format. The blocked condition produced significantly greater duration estimates and memory scores. The fact that memory scores paralleled apparent duration was interpreted as sup port for a storage size hypothesis. Poynter (1979) manipulated memory for stimulus information by filling a 195-sec interval with either 15 easy-to remember words or 15 hard-to-remember words. In addition, half of the subjects were given word prompts just prior to the time-estimation task. Sub jects presented with easily recalled words and mem ory prompts produced the longest time estimates and the best recall performance, again demon strating a parallel between the number of recalled stimulus events and perceived duration. The complexity of interval stimuli has also been shown to affect duration estimates. Mulligan and Schiffman (1979) and Ornstein (1969) demonstrated that providing a simplifying code for remembering complex line drawings reduced estimates of the stim ulus duration. The authors attributed this effect to a reduction in stimulus complexity. In addition, Schiffman and Bobko (1974) found that duration estimates of light-flash patterns were positively re lated to pattern complexity. Processing effort model. Avant, Lyman, and Antes (1975) presented letter stimuli for very brief intervals of time (30 msec), and found that dura tion estim (...truncated)