The changing face of police interrogation

This paper discusses some of the apparent changes in interrogations following the Police and Criminal Evidence Act 1984 and the introduction of tape recorders into police stations. These reforms are believed to have had several marked effects on interrogations. For example, the use of persuasive questioning is believed to have declined, as has the number of suspects making admissions. The evidence for these hypotheses is discussed. It is suggested that the apparent fall in confessions can be explained by methodological differences between studies and that the confession rate has in fact remained almost constant. Although there does appear to have been a change in the types of persuasive questioning employed during interrogations, it is difficult to establish whether or not the use of such questioning has declined. There is some evidence that persuasive questioning is now being carried out away from recording equipment.     

The changing face of Chinese immigrants in Canada

This paper analyzes the changing characteristics of Chinese immigrants to Canada between 1980 and 2001. It reveals that recent Chinese immigrants to Canada constitute a substantially different group from those of former years. They are no longer a homogeneous group from the rural areas of Mainland China, but in fact citizens of 132 countries, speaking 100 different languages and dialects. This study also reveals significant differences among Chinese subgroups. Given Canada’s time dependent immigration selection procedures, these differences are rationalized on the basis of a proposed single and double selection theory.     

The extraction of information from visual persistence.

Seven-letter targets were flashed for 50 msec and followed by either a blank adapting field (persisting representation of the stimulus fully available) or a series of continuous cycles of target and mask until the cumulative duration of the target matched the estimated duration of visual persistence (stimulus physically present for same interval as representation). The reportability of information from the targets in the latter case was only 50% that in the former. The interpretation is that visual persistence is an active, continuously operating process rather than a passive neural copy of the stimulus.     

The effect of spatial frequency and contrast on visual persistence

The visual persistence of sinusoidal gratings of varying spatial frequency and contrast was measured. It was found that the persistence of low-contrast gratings was longer than that of high-contrast stimuli for all spatial frequencies investigated. At higher contrast levels of 1 and 4 cycles deg-1 gratings, a tendency for persistence to be independent of contrast was observed. For 12 cycles deg-1 gratings, however, persistence continued to decrease with increasing contrast. These results are compared with recently published data on other temporal responses, and are discussed in terms of the different properties of sustained and transient channels.     

Self-esteem and persistence in the face of failure

In 2 studies, the authors examined self-esteem, persistence, and rumination in the face of failure. Study 1 manipulated degree of failure and availability of goal alternatives. When an alternative was available, high self-esteem (HSE) participants persisted more than low self-esteem (LSE) participants after a single failure, but less after repeated failure. When no alternative was available, no self-esteem differences in persistence emerged. LSE participants ruminated more than HSE participants. Study 2 examined persistence and rumination for 10 personal goals across an academic year. HSE participants were better calibrated (higher within-subject correlations between perceived progress and persistence across goals), had higher overall levels of persistence, higher grade point averages, and lower levels of rumination than LSE participants. Although traditional views that emphasize the tenacious persistence of HSE individuals need revision, HSE people appear more effective in self-regulating goal-directed behavior.     

Situational disengagement and persistence in the face of adversity

Research suggests that the experience of belonging to a group whose academic abilities are negatively stereotyped fosters disidentification over time, that is, the psychological insulation of the self from academic evaluations and outcomes (Crocker, Major, & Steele, 1998). This research tests whether the process of disidentification can ironically improve motivation when mobilized in response to specific situations. Black and White participants were given negative feedback on an ability-diagnostic or non-diagnostic task. Subsequently, all participants were given the opportunity to persist on the task and their level of disengagement was assessed. As hypothesized, Black participants in the diagnostic condition displayed the most persistence as well as the most disengagement and this persistence response was mediated by their disengagement. The results suggest that, in contrast to chronic disengagement, situational disengagement may help facilitate motivation and persistence.     

The existence and role of retinotopic and spatiotopic forms of visual persistence

Current theoretical conceptualizations of visual persistence fail to address the issue of its functional role. Based on extant experimental data we tentatively identify two general types of visual persistence: one resides in activity along the afferent visual pathway and is retinotopically organized; the other resides at central levels and is spatiotopically organized. Moreover, whereas the former afferent persistence is eliminated via saccadic suppression mechanisms in order to separate successive, retinotopic frames of pattern information, the latter, central one, in contrast, is generated and enhanced via extraretinal signals accompanying saccades in order to preserve phenomenal continuity of a stable spatiotopic representation of the environment from one fixation to the next.     

The role of visible persistence for perception of visual bilateral symmetry1

Abstract: Although the detection of visual bilateral symmetry has been claimed to be highly efficient, the possible involvement and function of visual memory in such efficient mechanisms has rarely been examined. We hypothesized that symmetry perception is rapid, as it can be achieved from rapidly decaying information of visible persistence. To test this hypothesis, we employed a temporal integration paradigm. A symmetric dot pattern was randomly divided into two asymmetric patterns and presented successively with a blank screen presented between patterns. Observers could detect symmetry when the two patterns were presented close in time (Experiment 1), indicating that observers perceived symmetry presumably utilizing visible persistence. In addition, the inverse‐intensity effect of visible persistence (Di Lollo & Bischof, 1995) was evident in our temporal integration task of symmetry (Experiment 2). The results of the current study clearly demonstrate that the detection of symmetry can be achieved based on the visible persistence. The large capacity and high spatial precision of visible persistence might be adequate for the rapid and spatially global encoding of visual symmetry.     

The contribution of visual persistence to the perceived duration of brief targets

Two experiments were conducted to examine the role of sensory persistence on tasks of perceived duration employing very brief visual stimuli. Using a standard temporal judgment task, the first experiment replicated both the “size effect” and “empty-filled” illusion reported by previous investigators. However, entirely comparable results were also found with a probematching task, which theoretically assesses the degree of persistence exhibited by a stimulus. The second experiment examined the effect of target luminance on perceived duration. Consistent with a sensory persistence interpretation, judgments of duration increased with increasing luminance. The results from the two experiments were discussed in terms of varying degrees of retinal persistence produced by different stimuli. This view was contrasted with currently dominant interpretations that postulate changes in perceived duration to reflect different information-processing requirements across stimulus conditions.     

Cortical dynamics of visual persistence and temporal integration

In a temporal integration experiment, subjects must integrate two visual stimuli, presented at separate times, to perform an identification task. Many researchers have assumed that the persistence of the leading stimulus determines the ability to integrate the leading and trailing stimuli. However, recent studies of temporal integration have challenged that hypothesis by demonstrating that several theories of persistence are incompatible with data on temporal integration. This paper shows that an account of visual persistence given by a neural network model of preattentive vision, called the boundary contour system, explains data on temporal integration. Computer simulations of the model explain why temporal integration becomes more difficult when the display elements are separated by longer interstimulus intervals or are of longer duration or of higher luminance, or are spatially closer together. The model suggests that different mechanisms underlie the inverse duration effects for leading and for trailing elements. The model further predicts interactions of spatial separation, duration, and luminance of the trailing display.     

Evidence for the persistence of visual guidance information

An earlier study from our laboratory provided initial support for the hypothesis that information facilitating visual guidance persists in the absence of retinal stimulation. The present study supports and extends this hypothesis with three experiments in which visually occluded subjects positioned a point of light at the location of a previously viewed target and also walked in the direction of a previously viewed path. In both tasks, performance was possible following occlusion, and in all cases, performance slowly and significantly decreased with longer durations of occlusion. This decay in performance was gradual and had a “half-life” of greater than 15 sec. Absolute performance was correlated across tasks. The effect of occlusion on absolute error in the localization performance was relatively stable within individuals over a 3-week period. The biological utility of guidance information persistence is discussed along with implications for space constancy, illusions of motion, and problems of disorientation.     

Two forms of persistence in visual information processing

Iconic memory, which was initially regarded as a unitary phenomenon, has since been subdivided into several components. In the present work we examined the joint effects of two such components (visible persistence and the visual analog representation) on performance in a partial report task. The display consisted of 15 alphabetic characters arranged around the perimeter of an imaginary circle on the face of an oscilloscope. The observer named the character singled out by a bar-probe. Two factors were varied: exposure duration of the array (10, 50, 100, 150, 200, 300, 400 or 500 ms) and duration of blank period (interstimulus interval, ISI) between the termination of the array and the onset of the probe (0, 50, 100, 150, or 200 ms). Performance was progressively impaired as both exposure duration and ISI were increased. The results were explained in terms of a probabilistic combinatorial model in which the timecourses of visible persistence and of the visual analog representation are regarded as time-locked to the onset and to the end of stimulation, respectively. The impairing effect of exposure duration was attributed to the relatively high spatial demands of the task that could be met optimally by information in visible persistence (which declines as a function of exposure duration), but less adequately by information in the visual analog representation. A second experiment, employing a task with lesser spatial demands, confirmed this interpretation.     

Evidence for visual persistence during saccadic eye movements

Summary 1. The persistence of visual perception was investigated under conditions of visual fixation as well as eye movement. The Ss' task was to discriminate brief double light impulses; their responses were recorded as a function of the duration of the interstimulus interval. Based on these data the critical interstimulus interval was calculated, which yielded equal response frequencies for the perception of one or two stimuli upon presentation of double light pulses.2. In the condition of visual fixation the two stimuli could not be discriminated until the mean value of interstimulus interval exceeded 73 msec. In the condition with eye movements, when the first stimulus was presented in the parafoveal region of the retina before the beginning of the saccade and the second stimulus in the foveal region just after termination of the eye movement, this duration was shown to be statistically of the same magnitude (76 msec).3. Possible alternative interpretations of this latter result, e.g., that it could be explained in terms of masking or saccadic suppression rather than visual persistence was discussed; it was attempted to invalidate such explanations by means of three control experiments.4. The main result, the persistence of visual perception during voluntary eye movements, was discussed in relation to the problem of spatial and temporal stability of visual perception.I thank Prof. Dr. H.W. Wendt for support in correcting the English translation.     

The relationship between visual persistence and event perception in bistable motion display

Observers viewed two alternating frames, each consisting of three rectangular bars displaced laterally by one cycle in one frame with respect to the other. At long interframe intervals (IFIs) observers perceived a group of three bars moving as a whole (group motion), and at short IFIs the overlapping elements in the two frames appeared stationary, while the third element appeared to move from one end of the display to the other (element motion). The upper temporal limit for perceiving element motion was reduced when bars with blurred edges were used and when either frame duration or bar size was increased. However, when inner and outer elements had different sizes, the element motion percept was dominant up to 230 ms IFI. These findings may be interpreted in terms of spatial tuning of motion mechanisms involved in the perception of bistable apparent motion.