Stimulus duration may affect partial report performance

Townsend, and Di Lollo and Moscovitch investigated the retention of item information in nearly identical variations of the partial report task. Whereas Townsend found a slight decrement in performance as the interval increased, Di Lollo and Moscovitch found a substantial increment. An experimental study of procedural differences that may have led to this discrepancy is reported. The results suggest that stimulus duration may have been responsible: Di Lollo and Moscovitch used extremely short durations (2 ms), while Townsend used longer durations (50 ms). This difference in durations may be important when the stimulus array and the partial report probe occur in close temporal contiguity.     

Isolating the interference caused by cue duration in partial report: A quantitative approach

In bar-probe partial report experiments, subjects are presented with a brief array of letters, followed by a cue that singles out a target letter. Using this procedure, V. M. Townsend (1973) reported a counterintuitive effect: As the duration of a cue was increased, target performance decreased dramatically. The aim of the present study was to isolate the locus of the cue-duration effect. To this end, several characteristics of the bar-probe display were manipulated in a single experiment: the interstimulus interval between the array and the cue, array density, the number of letters, and the number of symbols adjacent to the target. These factors were manipulated on a priori grounds so as to affect the different sources of information used in the bar-probe task--namely, durable storage, abstract identity information, and feature level information. The data were accurately fit by a simple quantitative, multinomial model that assumes that the different sources of information used in the bar-probe task make independent contributions to performance. The critical assumption of the model is that cue duration interferes with only one source of information--namely, feature level information.     

The effect of exposure duration on visual character identification in single, whole, and partial report

The psychometric function of single-letter identification is typically described as a function of stimulus intensity. However, the effect of stimulus exposure duration on letter identification remains poorly described. This is surprising because the effect of exposure duration has played a central role in modeling performance in whole and partial report (Shibuya & Bundesen, 1988). Therefore, we experimentally investigated visual letter identification as a function of exposure duration. We compared the exponential, the gamma, and the Weibull psychometric functions, all with a temporal offset included, as well as the ex-Gaussian, the log-logistic, and finally the squared-logistic, which is a psychometric function that to our knowledge has not been described before. The log-logistic and the squared-logistic psychometric function fit well to experimental data. Also, we conducted an experiment to test the ability of the psychometric functions to fit single-letter identification data, at different stimulus contrast levels; also here the same psychometric functions prevailed. Finally, after insertion into Bundesen's Theory of Visual Attention (Bundesen, 1990), the same psychometric functions enable closer fits to data from a previous whole and partial report experiment.     

Contextual effects in duration experience

The role of contextual factors on duration estimates was investigated, employing 6 time intervals ranging from 15 to 35 sec (demarcated by the onset and termination of a display panel of lights). When compared with earlier research, the results suggest that duration estimates are affected by the context of the stimulus intervals with regard to other stimuli in the series. Specifically, those stimuli that were overestimated when they were the shortest members of the series were underestimated when they were the longest intervals of the stimulus series. In addition, a lengthening effect was observed: duration estimates increased over blocks of trials for all stimulus intervals.     

Figurai vs. configural effects in the filled duration illusion

Patterns varying in form goodness and size were presented for 15, 30, and 45 msec. The experiment included three independent groups of subjects. Half of the first group were presented size variations with good figures, while the other half were shown size variations with poor figures. Half of the second group were presented goodness variations with small figures, while the other half were shown goodness variations with large figures. A third group experienced variations in both goodness and size. The major findings were: (1) poor figures and large figures were judged “longer” than good or small figures when varied within a session; (2) this effect vanished when the different levels of size or goodness were presented to separate groups of subjects; (3) the magnitude of the difference in temporal estimation was the same for size and goodness when each was varied in isolation; (4) when size and form goodness were varied orthogonally in the same session, both dimensions produced reliable changes in temporal estimation. These data are discussed in light of current theoretical explanations of the filled duration illusion.     

Presentation order effects in duration discrimination

Three separate experiments indicate that the second of a pair of durations tends to be overestimated relative to the first. These negative time-order errors are discussed as reliable perceptual phenomena, not explainable in terms of simple response biases, criterion biases, assimilation, or fading traces.     

Behavioral contrast in fixed-interval components: effects of extinction-component duration.

Seven albino rats were exposed to a multiple schedule of reinforcement in which the two components (fixed interval and extinction) alternated such that a presentation of the extinction component followed each fixed-interval reinforcement. In baseline sessions, the duration of the extinction component was constant and always one-third of the fixed-interval value. Probe sessions contained a probe segment in which the duration of the extinction component was increased; the response rate in fixed-interval components during the probe segment was compared with the response rate in the segments preceding and following the probe. The effect of increasing the duration of the extinction component was studied under three values of fixed interval: 30 s, 120 s, and 18 s, in three successive conditions. Response rate within fixed intervals was a direct function of duration of the extinction component. Pausing at the beginning of the fixed interval decreased as extinction duration increased. These effects were larger and more consistent for the shorter fixed-interval values (18 s and 30 s). These results indicate a functional relation between relative component duration and responding. For the component providing more frequent reinforcement, this could be stated as an inverse relationship between relative component duration and response rate. This relation is similar to findings regarding the ratio of trial and intertrial duration in Pavlovian conditioning procedures, and suggests that behavioral contrast may be related to Pavlovian contingencies underlying the multiple schedule.     

Iconic store and partial report

The iconic store has recently been challenged on the grounds that data in its favor may have resulted from some procedural artifacts. The display-instruction compatibility and perceptual grouping hypotheses were reexamined in two experiments with the partial-report paradigm. When care was taken to rectify some procedural problems found in Merikle’s (1980) study, it was established that the iconic store (as a hypothetical mechanism) can still be validly entertained. This report demonstrates one important procedural point in studying the iconic store with the partial report task, namely, that subjects must be given more than token training on the partial-report task.     

The effects of changing the phase and duration of sleep.

The relative effects of extended sleep, reduced sleep, and shifts of habitual sleep time on subsequent performance and mood were studied. Ten healthy male university students who regularly sleep 9.5-10.5 hr were the subjects. Measurements were obtained from a 45-min auditory vigilance task, a 5-min experimenter-paced addition task and a mood adjective check list 30 min after awakening, at midday, and in the evening following five electroencephalographically recorded nights of sleep. The experimental treatments compromised at 9.5-10.5 hr habitual sleep condition and four conditions in which the regular sleep period was lengthened, reduced, delayed, and advanced by 3hr. Following each 3-hr altered condition of sleep there was an equivalent decline in vigilance performance and in subjective arousal as measured by the mood scales. Together with other recent evidence, the present results support the hypothesis that acute disruption of the 24-hr sleep-wakefulness cycle produces degradations in human performance largely independent of total sleep time.     

Pairing effects and time-order errors in duration discrimination

Attention, Perception, & Psychophysics - The effects, measured in terms of reproductions, of pairing 4-sec-duration stimuli were examined for six ISIs varying between 1 and 26 sec. The results...     

Early and late selection in partial report: evidence from degraded displays.

In studies of iconic memory using the bar-probe task, subjects see a brief display of target letters and are probed by an arrow to report one of them. According to the classic early-selection account, subjects use the probe to select material for perceptual analysis from a precategorical (iconic) memory, but according to late-selection theories, subjects first identify the letters and then use the probe to select one letter for report from the set of categorized items. Pashler (1984) based his test for the locus of selection on a manipulation of display quality in previewed displays. He presented a target for 200 msec and then added a probe, together with the target, for an additional 150 msec. Reducing the target's stimulus quality increased response latency. If the subjects identified the characters before the probe appeared and then selected an item for report, the clarity of the original array should not have affected response latency. Hence, Pashler concluded that his subjects used the probe to select from a precategorical store (early selection). Pashler's experiment did not force subjects to rely on memory of the target; hence, although his experiment documented a situation in which subjects used early selection, it did not rule out late selection in studies of information persistence. We replicated Pashler's findings and, using his logic, showed that when subjects are forced to rely on memory of the target, they select from a categorized store.     

The effects of component duration on multiple-schedule performance in closed and open economies.

Pigeons responded on multiple variable-interval variable-interval schedules of reinforcement in an open and a closed economy. Equal duration components were increased in duration while the component rates of reinforcement were held constant, the component schedules were reversed, and component duration was decreased. In the open economy, daily sessions were limited to 1 hr, and subjects were maintained at 80% of their free-feeding weights through supplemental feeding when necessary in their home cages. In the closed economy, subjects were housed in their experimental chambers and no deprivation regimen was enforced. Relative response rate decreased as components were lengthened in the open economy, whereas in the closed economy relative rate increased as components were lengthened. Response proportions overmatched reinforcer proportions to a greater extent at long component durations in the closed economy, but there was no systematic effect of component duration on responding in the open economy.     

Disengaging attention: on the locus of the cue-duration effect in partial report.

Increasing cue duration impairs performance in bar-probe partial report when cues are presented peripherally, but not centrally (P. Dixon, R. Gordon, A. Leung, & V. Di Lollo, 1997). Three experiments examined whether this cue-duration effect reflects processes of exogenous attention. The effect of cue duration on partial report performance with peripheral, but not central, cues was replicated (Experiment 1). Further experiments manipulated the degree that exogenous versus endogenous modes of selection were favored and found that the cue-duration effect for peripheral cues was reduced (a) when blocks contained a high proportion of central cues (Experiment 2) and (b) when the color of the cue indicated the location of the target (Experiment 3). These findings challenge the view that the cue-duration effect is restricted to exogenous attention and are discussed in terms of the process of disengaging attention from the cue to reallocate attention to the target representation.     

Pattern and orientation effects on afterimage duration

Patterns composed of a pair of lines: vertical + horizontal, vertical + oblique, horizontal + oblique, and oblique + oblique, either centrally-aligned or edge-aligned, were shown at two positions of rotation. After a 1-s exposure to the pattern observers timed the duration of afterimages consisting of individual lines (fragmentary state) and the pattern as a whole (unitary state) for the ensuring 60 s. Summing unitary and fragmentary afterimage durations yielded the total afterimage duration for each pattern. Three hypotheses were confirmed by the results: (i) total afterimage duration is constant for all patterns when integrated spatiotemporal luminances are equal; (ii) unitary afterimage duration is also constant; (iii) fragmentary afterimages of vertically oriented lines have longer durations than either their horizontal or oblique pair members, regardless of alignment and, with one exception, rotation. For all patterns, the durations of the unitary and the fragmentary state represent a fixed portion of the total afterimage duration. The difference between afterimage duration for differently oriented lines in patterns which include a vertical is discussed in relation to the vertical-horizontal illusion, the function and structure of cortical orientation processes, and perceptual development.