Serial dependence in the estimation of a car's arrival time

Serial dependence of a car's arrival time. We have studied the sequential structure of data in the arrival- time estimations. Forty participants estimated the arrival-time of a vehicle under two experimental conditions: real car and video-image. Various time series regression models were fit to our data, and residuals autocorrelations were computed. For each serial-dependence model, data were fit to three functions, namely, power, logarithmic, and linear. In both experimental conditions, the response magnitude (R) on a given trial in t was a function of the stimulus intensity (S) in such a trial (t) and of the S and R on t-1 and t-2. Assimilation effect to the previous responses and contrast effect to the previous stimuli has been found.     

Serial position effects in implicit memory

Serial position effects in explicit and implicit memory were investigated in a noncolour word Stroop task. Participants were presented with a study list of four words printed in different colours and were tested for memory of the list position of the colour (explicit memory task); they were then asked to complete a word stem primed (or not primed) by one of the words in the study list (implicit memory task), a task presented as a distractor task. Serial position effects were observed in both explicit and implicit memory, for both response times and proportion of correct responses, with marked primacy effects, a drop in performance towards the third list position and a rise in memory performance at the fourth list position, the recency effect being most pronounced in implicit memory. It is concluded that explicit and implicit expressions of memory are governed by similar principles of temporal information processing.     

Serial position effects in the recall of picture sequences

Sequences of 10 pictures of familiar objects were presented for immediate recall, and typically bow-shaped serial position curves were obtained. The effects of redundant stimulus suffixes, and of redundant stimulus prefixes, which could be either extra pictures, or written words (the names of similar familiar objects) were examined. In the prefix conditions, extra words produced a general decrement over positions 1-4, as compared with a control condition. Picture prefixes had no effect. In the suffix conditions, redundant words affected positions 9 and 10, whereas the main effect of redundant pictures was at positions 8 and 9. The differential serial position effects are taken to reflect the presence of two memory codes, a verbal one and a visual one, which vary in trace-strength or accessibility at different list positions.     

Serial position functions for letter identification at brief and extended exposure durations

The properties of serial position functions for tachistoscopic report were investigated over a wide range of viewing times. Four-letter strings of random consonants were presented in varying display locations relative to the fixation point with the observers’ eye movements monitored to limit them to a single fixation for each display. Salient properties of the serial position curves include an overall central-peripheral gradient, higher performance at the ends than the interior of letter strings regardless of absolute location, and left-right asymmetry in the visual field, all of these being largely independent of viewing time. Errors reflecting loss of positional information are prominent even at extended viewing times, are more nearly symmetrical in the left and right visual fields than other types of errors, and, in contrast to item errors, occur less frequently in letter sequences that have high frequencies in English. Further, transposition errors exhibit a pronounced peripheral-to-central drift, possibly reflecting gradients of positional uncertainty. Such gradients may be implicated in the peripheral-central asymmetry of the lateral interference effects exerted by other letters on a target letter in a nonfoveal location.     

Serial position effects in high-speed memory search

Ss decided whether or not a test digit had occurred in a previously presented memory set. Decision time increased with the size of the memory set at equal linear rates for positive and negative responses. Positive decision times were sensitive to the serial position of the test digit. Together, these results are incompatible with serial-exhaustive models; some modifications are necessary in order to accommodate the obtained results.     

Taking a long look at action and time perception

Everyone has probably experienced chronostasis, an illusion of time that can cause a clock's second hand to appear to stand still during an eye movement. Though the illusion was initially thought to reflect a mechanism for preserving perceptual continuity during eye movements, an alternative hypothesis has been advanced that overestimation of time might be a general effect of any action. Contrary to both of these hypotheses, the experiments reported here suggest that distortions of time perception related to an eye movement are not distinct from temporal distortions for other kinds of responses. Moreover, voluntary action is neither necessary nor sufficient for overestimation effects. These results lead to a new interpretation of chronostasis based on the role of attention and memory in time estimation.     

Serial position effects in recall of television commercials

Does the position of a television commercial in a block of commercials determine how well it will be recalled? The findings of naturalistic studies can be affected by uncontrolled presentation, viewing, and retention variables. In the present article, college students viewed lists of 15 commercials in a laboratory simulation and recalled the product brand names. In an immediate test, the first commercials in a list were well recalled (a primacy effect), as were the last items (a recency effect), in comparison with the recall of middle items. In an end-of-session test, the primacy effect persisted, but the recency effect disappeared. Embedding lists within a television program again produced better recall of the first items during end-of-session tests of recall and recognition. These results offered convergent validity for the naturalistic studies of commercial memory, and they supported the usefulness of combining laboratory and field methods to answer questions about everyday memory.     

Motion versus position in the perception of head-centred movement

Abstract. Observers can recover motion with respect to the head during an eye movement by comparing signals encoding retinal motion and the velocity of pursuit. Evidently there is a mismatch between these signals because perceived head-centred motion is not always veridical. One example is the Filehne illusion, in which a stationary object appears to move in the opposite direction to pursuit. Like the motion aftereffect, the phenomenal experience of the Filehne illusion is one in which the stimulus moves but does not seem to go anywhere. This raises problems when measuring the illusion by motion nulling because the more traditional technique confounds perceived motion with changes in perceived position. We devised a new nulling technique using global-motion stimuli that degraded familiar position cues but preserved cues to motion. Stimuli consisted of random-dot patterns comprising signal and noise dots that moved at the same retinal 'base' speed. Noise moved in random directions. In an eye-stationary speed-matching experiment we found noise slowed perceived retinal speed as 'coherence strength' (ie percentage of signal) was reduced. The effect occurred over the two-octave range of base speeds studied and well above direction threshold. When the same stimuli were combined with pursuit, observers were able to null the Filehne illusion by adjusting coherence. A power law relating coherence to retinal base speed fit the data well with a negative exponent. Eye-movement recordings showed that pursuit was quite accurate. We then tested the hypothesis that the stimuli found at the null-points appeared to move at the same retinal speed. Two observers supported the hypothesis, a third partially, and a fourth showed a small linear trend. In addition, the retinal speed found by the traditional Filehne technique was similar to the matches obtained with the global-motion stimuli. The results provide support for the idea that speed is the critical cue in head-centred motion perception.     

Light source position in the perception of object shape

The apparent relief of monocularly viewed surfaces reversed when the order of light and shade was reversed relative to the position of a lamp observed the moment earlier. The pattern of shading was reversed either by illuminating from a direction opposite to that of the apparent direction of illumination or by inverting the illuminating image relative to the light source. The combination of both of these manipulations restores the original juxtaposition of light source and shading and reestablished accurate perception of relief. These results demonstrate that the perception of the relief of physical surfaces depends upon the remembered position of an apparent light source.     

Serial position effects in recognition memory for odors

Five experiments examined recognition memory for sequentially presented odors. Participants were presented with a sequence of odors and then had to identify an odor from the list in a test probe containing 2 odors. All experiments demonstrated enhanced recognition of odors presented at the start and end of a series, compared with those presented in the middle of the series when a 3-s retention interval between list termination and test was used. In Experiments 2 and 3, when a 30-s or 60-s retention interval was used, participants performed at slightly lower levels, although the serial position function was similar to that obtained with the 3-s retention interval. These results were noted with a 5-item (Experiments 1 and 4), 7-item (Experiment 2), 6-item (Experiment 3), and 4-item (Experiment 5) list of odors. As the number of test trials increased, recognition performance decreased, indicating a strong role for olfactory fatigue or interference in these procedures. A verbal suppression task, used in Experiments 4 and 5, had little influence on serial-position-based performance.     

Causality and the perception of time

Does our perception of when an event occurs depend on whether we caused it? A recent study suggests that when we perceive our actions to cause an event, it seems to occur earlier than if we did not cause it.     

Routine and the perception of time

The authors investigated the influence of routine on people's estimation of time, testing the hypothesis that duration is remembered as being shorter when time is spent in a routine activity. In 4 experiments and 2 field studies, the authors compared time estimations in routine and nonroutine conditions. Routine was established by a sequence of markers (Study 1), variation of the task (Studies 2 and 3), or the number of repetitive blocks (Study 4). As hypothesized, the duration of the task was remembered as being shorter in routine conditions than in nonroutine ones. This trend was reversed in experienced (prospective) judgments when participants were informed beforehand of the duration-judgment task (Study 3). In Studies 5 and 6, the authors examined remembered duration judgments of vacationers and kibbutz members, which provided further support for the main hypothesis.     

The perception of time

The present paper organizes and evaluates selected portions of the time perception literature. Emphasis is on data and theory concerned primarily with judgments of brief temporal intervals. Research concerning the psychophysical law for time, Weber’s law, the time-order error, and the role of nontemporal information is evaluated. This is followed by a consideration of current, quantitatively oriented, theoretical formulations for time perception.     

Cerebral asymmetry in time perception

Eighteen right-handed male subjects estimated the duration of dot patterns of varying numerosity which were briefly flashed to the left and right visual fields. The mean judged duration of patterns flashed to the left visual field was significantly less than the mean judged duration of patterns flashed to the right visual field. However, the duration of all patterns was underestimated, regardless of visual field. In addition, apparent duration increased linearly when plotted as a function of log duration and increased monotonically when plotted as a function of stimulus numerosity. Overall accuracy was nearly equivalent in both visual fields, but there were interactions between actual durations and visual field and between numerosity and visual field. Thomas and Weaver’s [1975) model for time perception is applied to the data, and it is suggested that the left hemisphere relies on a timer to estimate duration, while the right hemisphere relies on a visual information processor to estimate duration. nt]mis|The author would like to thank A. B. Kristofferson, S. F. Witelson, an anonymous referee, Mary Kay Fortman, and Allen Gouse for their helpful comments. Some of these data were presented at the meeting of the Midwestern Psychological     

Sequential effects in time perception

Taylor and Lupker (2001) reported that in a naming task, stimuli were named more rapidly when preceded by an easy-to-name stimulus than when preceded by a difficult-to-name stimulus (sequential effects). The goal of the present research was to investigate whether sequential effects could be explained in terms of time perception processes (within the context of Lupker, Brown, and Colombo’s [1997] time criterion account). Participants were required to name easy and difficult stimuli (high-frequency words and nonwords in Experiment 1; words only in Experiment 2). Each naming trial was followed by a set of asterisks (*****). The participants were required to press a button when they thought the asterisks had been presented for exactly 1 sec. Time intervals produced after naming difficult stimuli were longer than time intervals produced after naming easy stimuli. That is, time perception was affected by the difficulty of word/nonword naming in a way that carried over to the next stimulus, supporting the idea that carryover effects in time perception may be the source of sequential effects in the naming task.