Kenneth C. Scott-Brown

Assessing the importance of letter pairs in initial, exterior, and interior positions in reading.

Exterior letter pairs (e.g., d--k in dark) play a major role in single-word recognition, but other research (D. Briihl & A. W. Inhoff, 1995) indicates no such role in reading text. This issue was examined by visually degrading letter pairs in three positions in words (initial, exterior, and interior) in text. Each degradation slowed reading rate compared with an undegraded control. However, whereas degrading initial and interior pairs slowed reading rate to a similar extent, degrading exterior pairs slowed reading rate most of all. Moreover, these effects were obtained when letter identities across pair positions varied naturally and when they were matched. The findings suggest that exterior letter pairs play a preferential role in reading, and candidates for this role are discussed.

The Illusory-Letters Phenomenon: An Illustration of Graphemic Restoration in Visual Word Recognition

We present a demonstration of word perception in which stimuli containing very few letters (just 50% of their original number) are presented for unlimited durations and yet are seen unequivocally as complete words. The phenomenon suggests that recognition of words can be achieved even when perception of their component letters is prevented.

Contrast discrimination, non–uniform patterns and change blindness

Change blindness–our inability to detect large changes in natural scenes when saccades, blinks and other transients interrupt visual input–seems to contradict psychophysical evidence for our exquisite sensitivity to contrast changes. Can the type of effects described as ‘change blindness’ be observed with simple, multi–element stimuli, amenable to psychophysical analysis? Such stimuli, composed of five mixed contrast elements, elicited a striking increase in contrast increment thresholds compared to those for an isolated element. Cue presentation prior to the stimulus substantially reduced thresholds, as for change blindness with natural scenes. On one hand, explanations for change blindness based on abstract and sketchy representations in short–term visual memory seem inappropriate for this low–level image property of contrast where there is ample evidence for exquisite performance on memory tasks. On the other hand, the highly increased thresholds for mixed contrast elements, and the decreased thresholds when a cue is present, argue against any simple early attentional or sensory explanation for change blindness. Thus, psychophysical results for very simple patterns cannot straightforwardly predict results even for the slightly more complicated patterns studied here.

Looking for trouble: A description of oculomotor search strategies during live CCTV operation.

Recent research has begun to address how CCTV operators in the modern control room attempt to search for crime (e.g., Howard et al., 2011). However, an often-neglected element of the CCTV task is that the operators have at their disposal a multiplexed wall of scenes, and a single spot-monitor on which they can select any of these feeds for inspection. Here we examined how 2 trained CCTV operators used these sources of information to search from crime during a morning, afternoon, and night-time shift. We found that they spent surprisingly little time viewing the multiplex wall, instead preferentially spending most of their time searching on the single-scene spot-monitor. Such search must require a sophisticated understanding of the surveilled environment, as the operators must make their selection of which screen to view based on their prediction of where crime is likely to occur. This seems to be reflected in the difference in the screens that they selected to view at different times of the day. For example, night-clubs received close monitoring at night, but were seldom viewed in mid-morning. Such narrowing of search based on a contextual understanding of an environment is not a new idea (e.g., Torralba et al., 2006), and appears to contribute to operators selection strategy. This research prompts new questions regarding the nature of representation that operators have of their environment, and how they might develop expectation-based search strategies to countermand the demands of the large influx of visual information. Future research should ensure not to neglect examination of operator behavior “in the wild” (Hutchins, 1995a), as such insights are difficult to gain from laboratory based paradigms alone.

An Instinct for Detection: Psychological Perspectives on CCTV Surveillance

The aim of this article is to inform and stimulate a proactive, multidisciplinary approach to research and development in surveillance-based detective work. In this article we review some of the key psychological issues and phenomena that practitioners should be aware of. We look at how human performance can be explained with reference to our biological and evolutionary legacy. We show how critical viewing conditions can be in determining whether observers detect or overlook criminal activity in video material. We examine situations where performance can be surprisingly poor, and cover situations where, even once confronted with evidence of these detection deficits, observers still underestimate their susceptibility to them. Finally we explain why the emergence of these relatively recent research themes presents an opportunity for police and law enforcement agencies to set a new, multidisciplinary research agenda focused on relevant and pressing issues of national and international importance.

Depth perception not found in human observers for static or dynamic anti-correlated random dot stereograms.

One of the greatest challenges in visual neuroscience is that of linking neural activity with perceptual experience. In the case of binocular depth perception, important insights have been achieved through comparing neural responses and the perception of depth, for carefully selected stimuli. One of the most important types of stimulus that has been used here is the anti-correlated random dot stereogram (ACRDS). In these stimuli, the contrast polarity of one half of a stereoscopic image is reversed. While neurons in cortical area V1 respond reliably to the binocular disparities in ACRDS, they do not create a sensation of depth. This discrepancy has been used to argue that depth perception must rely on neural activity elsewhere in the brain. Currently, the psychophysical results on which this argument rests are not clear-cut. While it is generally assumed that ACRDS do not support the perception of depth, some studies have reported that some people, some of the time, perceive depth in some types of these stimuli. Given the importance of these results for understanding the neural correlates of stereopsis, we studied depth perception in ACRDS using a large number of observers, in order to provide an unambiguous conclusion about the extent to which these stimuli support the perception of depth. We presented observers with random dot stereograms in which correlated dots were presented in a surrounding annulus and correlated or anti-correlated dots were presented in a central circular region. While observers could reliably report the depth of the central region for correlated stimuli, we found no evidence for depth perception in static or dynamic anti-correlated stimuli. Confidence ratings for stereoscopic perception were uniformly low for anti-correlated stimuli, but showed normal variation with disparity for correlated stimuli. These results establish that the inability of observers to perceive depth in ACRDS is a robust phenomenon.

Behavioral biases when viewing multiplexed scenes: scene structure and frames of reference for inspection

Where people look when viewing a scene has been a much explored avenue of vision research (e.g., see Tatler, 2009). Current understanding of eye guidance suggests that a combination of high and low-level factors influence fixation selection (e.g., Torralba et al., 2006), but that there are also strong biases toward the center of an image (Tatler, 2007). However, situations where we view multiplexed scenes are becoming increasingly common, and it is unclear how visual inspection might be arranged when content lacks normal semantic or spatial structure. Here we use the central bias to examine how gaze behavior is organized in scenes that are presented in their normal format, or disrupted by scrambling the quadrants and separating them by space. In Experiment 1, scrambling scenes had the strongest influence on gaze allocation. Observers were highly biased by the quadrant center, although physical space did not enhance this bias. However, the center of the display still contributed to fixation selection above chance, and was most influential early in scene viewing. When the top left quadrant was held constant across all conditions in Experiment 2, fixation behavior was significantly influenced by the overall arrangement of the display, with fixations being biased toward the quadrant center when the other three quadrants were scrambled (despite the visual information in this quadrant being identical in all conditions). When scenes are scrambled into four quadrants and semantic contiguity is disrupted, observers no longer appear to view the content as a single scene (despite it consisting of the same visual information overall), but rather anchor visual inspection around the four separate “sub-scenes.” Moreover, the frame of reference that observers use when viewing the multiplex seems to change across viewing time: from an early bias toward the display center to a later bias toward quadrant centers.

Detect the unexpected: a science for surveillance

Purpose – The purpose of this paper is to outline a strategy for research development focused on addressing the neglected role of visual perception in real life tasks such as policing surveillance and command and control settings.Design/methodology/approach – The scale of surveillance task in modern control room is expanding as technology increases input capacity at an accelerating rate. The authors review recent literature highlighting the difficulties that apply to modern surveillance and give examples of how poor detection of the unexpected can be, and how surprising this deficit can be. Perceptual phenomena such as change blindness are linked to the perceptual processes undertaken by law‐enforcement personnel.Findings – A scientific programme is outlined for how detection deficits can best be addressed in the context of a multidisciplinary collaborative agenda between researchers and practitioners. The development of a cognitive research field specifically examining the occurrence of perceptual “failu...

Changing the View: Towards the Theory of Visualisation Comprehension

The core problem of the evaluation of Information Visualisation is that the end product of visualisation – the comprehension of the information from the data – is difficult to measure objectively. This paper outlines a description of visualisation comprehension based on two existing theories of perception: Principles of Perceptual Organisation and the Reverse Hierarchy Theory. The resulting account of the processes involved in visualisation comprehension enables evaluation that is not only objective, but also non-comparative, providing an absolute efficiency classification. Finally, as a sample application of this approach, an experiment studying the benefits of interactivity in 3D scatterplots is presented.

Choreographing emotional facial expressions

Realistic character animation requires elaborate rigging built on top of high quality 3D models. Sophisticated anatomically based rigs are often the choice of visual effect studios where life-like animation of CG characters is the primary objective. However, rigging a character with a muscular-skeletal system is very involving and time-consuming process, even for professionals. Although, there have been recent research efforts to automate either all or some parts of the rigging process, the complexity of anatomically based rigging nonetheless opens up new research challenges. We propose a new method to automate anatomically based rigging that transfers an existing rig of one character to another. The method is based on a data interpolation in the surface and volume domain, where various rigging elements can be transferred between different models. As it only requires a small number of corresponding input feature points, users can produce highly detailed rigs for a variety of desired character with ease. Copyright