Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

The impact of cognitive styles on perceptual distributed multimedia quality

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2003 John Wiley & Sons, Inc.Multimedia technology has been widely used in web-based instruction, but previous studies have indicated that individual differences, especially cognitive styles, have significant effects on users’ preferences with respect to presentation of multimedia content. However, such research has thus far neglected to examine the effect of cognitive styles on users’ subjective perceptions of multimedia quality. This study aims to examine the relationships among users’ cognitive styles, the multimedia Quality of Service (QoS) delivered by the underlying network, and Quality of Perception (QoP), which encompasses user levels of enjoyment and understanding of the informational content provided by multimedia material. Accordingly, 132 users took part in an experiment in which they were shown multimedia video clips presented with different values of two QoS parameters (frame rate and colour depth). Results show that, whilst the two QoS parameters do not impact user QoP, multimedia content and dynamism levels significantly influence the user understanding and enjoyment component of QoP

Induced Gamma-band Activity Elicited by Visual Representation of Unattended Objects

Peer reviewedPostprin

A study of user perceptions of the relationship between bump-mapped and non-bump-mapped materials, and lighting intensity in a real-time virtual environment

The video and computer games industry has taken full advantage of the human sense of vision by producing games that utilize complex high-resolution textures and materials, and lighting technique. This results to the creation of an almost life-like real-time 3D virtual environment that can immerse the end-users. One of the visual techniques used is real-time display of bump-mapped materials. However, this sense of visual phenomenon has yet to be fully utilized for 3D design visualization in the architecture and construction domain. Virtual environments developed in the architecture and construction domain are often basic and use low-resolution images, which under represent the real physical environment. Such virtual environment is seen as being non-realistic to the user resulting in a misconception of the actual potential of it as a tool for 3D design visualization. A study was conducted to evaluate whether subjects can see the difference between bump-mapped and nonbump-mapped materials in different lighting conditions. The study utilized a real-time 3D virtual environment that was created using a custom-developed software application tool called BuildITC4. BuildITC4 was developed based upon the C4Engine which is classified as a next-generation 3D Game Engine. A total of thirty-five subjects were exposed to the virtual environment and were asked to compare the various types of material in different lighting conditions. The number of lights activated, the lighting intensity, and the materials used in the virtual environment were all interactive and changeable in real-time. The goal is to study how subjects perceived bump-mapped and non-bump mapped materials, and how different lighting conditions affect realistic representation. Results from this study indicate that subjects could tell the difference between the bump-mapped and non-bump mapped materials, and how different material reacts to different lighting condition

Traditional and new principles of perceptual grouping

Perceptual grouping refers to the process of determining which regions and parts of the visual scene belong together as parts of higher order perceptual units such as objects or patterns. In the early 20th century, Gestalt psychologists identified a set of classic grouping principles which specified how some image features lead to grouping between elements given that all other factors were held constant. Modern vision scientists have expanded this list to cover a wide range of image features but have also expanded the importance of learning and other non-image factors. Unlike early Gestalt accounts which were based largely on visual demonstrations, modern theories are often explicitly quantitative and involve detailed models of how various image features modulate grouping. Work has also been done to understand the rules by which different grouping principles integrate to form a final percept. This chapter gives an overview of the classic principles, modern developments in understanding them, and new principles and the evidence for them. There is also discussion of some of the larger theoretical issues about grouping such as at what stage of visual processing it occurs and what types of neural mechanisms may implement grouping principles

Associating object names with descriptions of shape that distinguish possible from impossible objects.

Five experiments examine the proposal that object names are closely linked torepresentations of global, 3D shape by comparing memory for simple line drawings of structurally possible and impossible novel objects.Objects were rendered impossible through local edge violations to global coherence (cf. Schacter, Cooper, & Delaney, 1990) and supplementary observations confirmed that the sets of possible and impossible objects were matched for their distinctiveness. Employing a test of explicit recognition memory, Experiment 1 confirmed that the possible and impossible objects were equally memorable. Experiments 2–4 demonstrated that adults learn names (single-syllable non-words presented as count nouns, e.g., “This is a dax”) for possible objectsmore easily than for impossible objects, and an item-based analysis showed that this effect was unrelated to either the memorability or the distinctiveness of the individual objects. Experiment 3 indicated that the effects of object possibility on name learning were long term (spanning at least 2months), implying that the cognitive processes being revealed can support the learning of object names in everyday life. Experiment 5 demonstrated that hearing someone else name an object at presentation improves recognition memory for possible objects, but not for impossible objects. Taken together, the results indicate that object names are closely linked to the descriptions of global, 3D shape that can be derived for structurally possible objects but not for structurally impossible objects. In addition, the results challenge the view that object decision and explicit recognition necessarily draw on separate memory systems,with only the former being supported by these descriptions of global object shape. It seems that recognition also can be supported by these descriptions, provided the original encoding conditions encourage their derivation. Hearing an object named at encoding appears to be just such a condition. These observations are discussed in relation to the effects of naming in other visual tasks, and to the role of visual attention in object identification

The Effect of Size Upon Haptic Shape Discrimination

Object shape perception is fundamentally important for daily life. It has been suggested (e.g., Gibson, 1962) that the visual and haptic modalities are equivalent with regards to the ability to perceive shape. Norman et al. (2012) showed that visual and haptic shape discrimination accuracies are indeed comparable. Craddock and Lawson (2009) found that haptic shape discrimination performance was adversely affected by a size change. However, this result was obtained for man-made objects (i.e., bathtubs and benches). The purpose of the current investigation was to determine whether size changes also reduce haptic shape discrimination accuracy for naturally-shaped objects. On any given trial, adult participants haptically explored two bell pepper replicas and judged whether they possessed the same or different shapes. In one condition, the two explored objects were of the same overall size, while in two other conditions, the objects differed in size (either by smaller or larger amounts). The results indicated that while size changes do have negative effects upon haptic shape discrimination, larger magnitude size changes do not hurt performance any more than smaller size changes. Although visual shape discrimination is not appreciably affected by size change (e.g., Landau & Leyton, 1999; Norman, Swindle, Jennings, Mullins, & Beers, 2009) and haptic shape discrimination of man-made objects is adversely affected by size change (Craddock & Lawson, 2009), the current results demonstrate that the haptic system can indeed tolerate some object size change without impairment in human discrimination performance

Getting the message across : ten principles for web animation

The growing use of animation in Web pages testifies to the increasing ease with which such multimedia components can be created. This trend indicates a commitment to animation that is often unmatched by the skill of the implementers. The present paper details a set of ten commandments for web animation, intending to sensitise budding animators to key aspects that may impair the communicational effectiveness of their animation. These guidelines are drawn from an extensive literature survey coloured by personal experience of using Web animation packages. Our ten principles are further elucidated by a Web-based on-line tutorial