Prime time: fatigue and set effects in the perception of reversible figures.

Subjects viewed unambiguous versions of both stationary and rotating Necker cube illusions for varying durations prior to the presentation of the standard ambiguous figure. In each case, the subjects were more likely to report the ambiguous figure to be (1) in the same configuration as that of the preceding prime following brief preexposure periods and (2) in the opposite configuration from that of the preceding prime following long preexposure periods. In addition, the number of reversals of the figure during the test period was also strongly related to the duration of the preexposure period, with progressively fewer reversals reported following longer preexposure periods. The results are interpreted as revealing the concurrent roles of "set" effects in the brief preexposure conditions and neural fatigue effects in the long preexposure conditions. Furthermore, the ability of the proposed two-process model to integrate the myriad of empirical effects in the reversible-figure literature is emphasized.     

Ambiguity and structural information in the perception of reversible figures

The perspective reversals elicited by a set of drawings based on the Mach truncated pyramid are examined. We obtained each pattern of the set from the previous one by adding to it some graphic cues, which were easily integrated into one of the two competing interpretations, thus reducing step by step the ambiguity of the basic pattern. The phenomenological model, proposed to link the mean times of both alternative interpretations with their complexities, is in close agreement with our experimental data. Furthermore, different aspects of such data are well described by the model equations: The measure of the prevalence of the supported interpretation is well correlated with the difference in complexity between the two alternative interpretations; the two different trends of the mean time of the unfavored interpretation, found in the data obtained from different observers as a function of the various patterns of the set, are well fitted by the model without the need for any specific additional hypothesis.     

Configural biases and reversible figures: evidence of multilevel grouping effects

Four experiments sought to identify the processes underlying 2 classes of grouping effects that are readily produced with a hierarchical figure type known as ambiguous triangles. Previous work has shown that aligning small equilateral triangles in particular configurations can both facilitate and interfere with observers' ability to report the pointing direction of the individual triangles. We determined that selectively adapting the observer to low-frequency gratings of the same orientation as the aligned triangles markedly altered the interfering and facilitative effects of the global configuration only when an accuracy measure of performance was used. When a response latency measure was used, no effect of the same adaptation condition was found. Results are discussed in terms of multiple levels of grouping effects in the visual system and the differential sensitivity of these levels to basic neural adaptation.     

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.     

Age effects in perception of time

Despite the widespread belief that the subjective speed of the passage of time increases with age, empirical results are controversial. In this study, a combination of questionnaires was employed to assess subjective time perception by 499 subjects, ages 14 to 94 years. Pearson correlations and nonlinear regression analyses on a variety of questionnaires and the age of the participants show that the momentary perception of the passage of time and the retrospective judgment of past periods of time are a function of chronological age; however, small-to-moderate effects accounted for at most 10% of the variance. Results generally support the widespread perception that the passage of time speeds up with age. These results are discussed in the context of models of prospective and retrospective time judgment, but interpretations have to be treated with caution given methodological limitations.     

Asymmetric cross-modal effects in time perception

It is common to judge the duration of an audiovisual event, and yet it remains controversial how the judgment of duration is affected by signals from other modalities. We used an oddball paradigm to examine the effect of sound on the judgment of visual duration and that of a visual object on the judgment of an auditory duration. In a series of standards and oddballs, the participants compared the duration of the oddballs to that of the standards. Results showed asymmetric cross-modal effects, supporting the auditory dominance hypothesis: a sound extends the perceived visual duration, whereas a visual object has no effect on perceived auditory duration. The possible mechanisms (pacemaker or mode switch) proposed in the Scalar Expectancy Theory [Gibbon, J., Church, R. M., & Meck, W. H. (1984). Scalar timing in memory. In J. Gibbon & L. Allan (Eds.), Annals of the New York Academy of Sciences: Vol. 423. Timing and time perception (pp. 52–77). New York: New York Academy of Sciences] were examined using different standard durations. We conclude that sound increases the perceived visual duration by accelerating the pulse rate in the visual pacemaker.     

Perceptual ambiguity and stability of reversible figures

In this work, the results of two experiments on ambiguous patterns are reported, which have been obtained by presenting a series of stimuli designed, in both cases, to reduce gradually the ambiguity of the patterns. Such reduction has been performed by respectively increasing or decreasing the amount of graphic details in the experiments. Data of both experiments show a lengthening of mean reversal time. The increase in the stability of one percept can be regarded as associated with the increasing difficulties encountered by an observer in organizing and restating the alternative "hypothesis" through the perceptual mechanisms. The loss of balance in the durations of percepts is discussed in terms of their different informational contents. Finally, in Exp. 1 an analysis is made to evaluate to what extent an addition of perceptual cues, designed to reinforce a three-dimensional interpretation of a pattern, can influence its figure-ground alternation.     

Area perception in simple geometrical figures

The results of experiments on visual perception of area of circles and squares are reported. Pairs of geometrical figures were presented simultaneously on an oscilloscope screen. While one of them was fixed, the other one was controlled by an experimental subject. The task of the subject was to match the area of the variable figure to the area of the fixed one. The obtained data show underestimation of the area of circle when compared with square. A mathematical model designed to explain this phenomenon is proposed here. The image function defined as a low-pass filtered (blurred) version of the figure is employed for this purpose. Then, instead of the position of the image function maxima, the position of a threshold value is used for area computation.     

Holistic processes in the perception and transformation of disoriented figures

Two experiments tested whether mental rotation of complex, hierarchical stimuli occurs holistically or separately at global and local levels of structure. Large (global) letters were constructed from spatial arrangements of small (local) letters. Reflection conditions (normal vs. reflected) were produced by varying the two levels independently. The task was structured so that subjects could rotate one level of the stimulus in some conditions but had to rotate both levels in other conditions. Experiment 1 showed that rotation rate was not affected by the number of levels that had to be rotated to make a reflection decision. This result implies that the rotation of global and local levels occurred together rather than sequentially. Experiment 2 showed that the rotation of the two levels was holistic as opposed to parallel and independent. The results also demonstrate that global information is processed faster than local information regardless of whether or not a rotation is performed. These findings are discussed in relation to theories of mental rotation and global precedence.     

Enduring interest in perceptual ambiguity: alternating views of reversible figures

Research favoring the so-called bottom-up and top-down classes of explanations for reversible figures that dominated the literature in last half of the 20th century is reviewed. Two conclusions are offered. First, any single-process model is extremely unlikely to be able to accommodate the wide array of empirical findings, suggesting that the "final" explanation will almost certainly involve a hybrid conceptualization of interacting sensory and cognitive processes. Second, the utility of distinguishing between 2 components of the observer's experience with reversible figures is emphasized. This distinction between the observer's ability to access multiple representations from the single stimulus pattern (ambiguity) and the observer's phenomenal experience of oscillation between those representations (reversibility) permits the literature to be segregated into useful categories of research that expose overlapping but distinctive cortical processes.     

The recency effect in the perception of ambiguous figures

After a failure to obtain a recency effect in the perception of ambiguous figures three experiments were carried out to determine the conditions which govern the effect. It was found that the duration of the stimulus which precedes the ambiguous figure (the most recent stimulus) was important. Also of importance was the interval between the next-to-most-recent stimulus and the ambiguous figure. The effect of manipulating these variables was such that sometimes no recency effect was obtained, implying that their state is sometimes critical for the effect. Variations in the duration of the ambiguous stimulus did not cause the recency effect to vary. Recommendations are made for the demonstration of a reliable recency effect.     

Attentional processes in time perception: effects of mental workload and event structure

The role of attention in timing was evaluated in 2 experiments. In Experiment 1, participants reproduced the durations of melodies with either a coherent or an incoherent structure. Participants were tested under control (timing only) and detection (timing plus target detection) workload conditions. Reproductions were shorter and more inaccurate under detection conditions, and incoherent event structure extended the effect to a wider range of durations. In Experiment 2, participants reproduced the durations of auditory prose passages that represented 3 levels of mental workload and 3 levels of event structure. Both increases in workload and the degradation of structure led to inaccurate reproductions. The results point to the central role of attention in temporal experience.     

适应性时间管理：死亡意识对时间知觉和跨期决策的影响

死亡意识是个体对自身死亡必然性的认识; 基于进化适应性的考量, 作者认为具有前瞻性的死亡意识作为人类特有的认知能力和个体生命史的终极坐标, 不仅可能引起恐惧感和防御反应, 更重要的是可以帮助人们做出适应性的时间管理。据此推论, 死亡意识的启动会加强人们对时间有限性的关注, 体验出更强的时间流逝感, 影响人们对时间的评估, 以及人们对不同时间点的成本与收益进行权衡而做出的跨期决策。本研究采用死亡凸显范式启动死亡意识, 通过两个实验探讨了死亡意识、时间知觉和跨期决策三者之间的关系。结果发现, 死亡意识启动使被试低估时间距离, 并表现出较低的跨期决策延迟折扣率, 从而在较小的即时获益与更大的延迟的获益之间更为偏好未来导向的选项。进一步的分析显示, 时间知觉在死亡意识和跨期决策延迟折扣率之间起到部分中介变量的作用。以上的研究结果初步揭示了死亡意识在时间管理上的适应性价值。     

The role of discontinuities in the perception of subjective figures

Recently we proposed a theory of visual interpolation (Kellman & Shipley, in press) that addresses a variety of unit formation phenomena, including the perception of partly occluded objects and subjective figures. A basic notion of the theory is that discontinuities in the first derivative of projected edges are the initiating conditions for interpolation of boundaries that are not physically specified. In this paper, we report four experiments in which this claim was tested in the domain of subjective figures. Experiments 1 and 2 demonstrate that discontinuities in the first derivative of the edges of inducing elements have a clear effect on the frequency of report and the perceived clarity of simple subjective figures. Similar effects are found when unfamiliar subjective figures and inducing elements are used (Experiment 3). Experiment 4 rules out the possibility that the discontinuities in the first derivative merely add to the clarity of subjective figures. These experiments suggest that first-order discontinuities play a central role in unit formation.