Complete mergeability and amodal completion.

When image fragments are taken to correspond to the visible portions of a single occluded object, the object is said to 'amodally complete' behind the occluder. Kellman and Shipley (Kellman, P. J., & Shipley, T. F. (1991). A theory of visual interpolation in objective perception. Cognitive Psychology, 23, 144-221) argued that when the virtual contour extensions of such image fragments subtend an obtuse or right angle, the contours are 'relatable' and therefore complete. However, edge and surface relatability are neither necessary nor sufficient for completion to be perceived (Tse, P. U. (1999) Volume completion. Cognitive Psychology). Evidence is offered that completion is not driven directly by image cues such as contour relatability, but is driven, rather, by intermediate representations, such as volumes that are inferred from global image cue relationships. Evidence suggests that several factors, none of which is necessary for amodal completion to occur, contribute to the perceived strength of amodal completion, including similarity of pattern or substance, proximity, and good volume continuation or complete mergeability. Two partially occluded volumes are completely mergeable when they can be extended into occluded space along the trajectory defined by their visible surfaces such that they merge entirely with each other. Mergeability is not measurable in the image because it describes an inferred relationship among volumes that must themselves be inferred from the image.     

Wakes and spokes: new motion-induced brightness illusions

Under certain conditions, high-contrast moving figures induce adjacent illusory regions, 'wakes' and 'spokes', which have contrast polarity opposite the inducing figures. In this paper we document properties of these novel phenomena. When the illusions are induced by a moving bar, spokes appear on the side of the bar closer to fixation and connect the bar to the fixation point, regardless of the momentary position of the bar or whether it is moving to the left or to the right. Although spokes often extend up to the fixation point, they never extend beyond it. This is not due to blocking of the spoke's spread by the fixation point, because in another experiment spokes extend directly through an intervening figure. Whereas spokes emanate from the end of a horizontally moving bar closest to fixation, wakes emanate from the end farthest from fixation. In contrast to spokes, wakes do not show a towards-fixation bias. Instead, the wake's end trails the position of the bar, like a ship's wake. The higher the bar velocity, the more the end of the wake appears to trail it, suggesting that wakes are caused by a process which spreads from the edge of moving figures. Wakes and spokes, as distinct illusions, should provide significant constraints on theories of human motion and brightness perception processes.     

The whole moves less than the spin of its parts

When individually moving elements in the visual scene are perceptually grouped together into a coherently moving object, they can appear to slow down. In the present article, we show that the perceived speed of a particular global-motion percept is not dictated completely by the speed of the local moving elements. We investigated a stimulus that leads to bistable percepts, in which local and global motion may be perceived in an alternating fashion. Four rotating dot pairs, when arranged into a square-like configuration, may be perceived either locally, as independently rotating dot pairs, or globally, as two large squares translating along overlapping circular trajectories. Using a modified version of this stimulus, we found that the perceptually grouped squares appeared to move more slowly than the locally perceived rotating dot pairs, suggesting that perceived motion magnitude is computed following a global analysis of form. Supplemental demos related to this article can be downloaded from app.psychonomic-journals.org/content/supplemental.     

The use of health technology and information: e-learning technological approach.

The Internet is becoming the preferred place for finding information. Millions of people go online in search of health and medical information. Likewise, health care professionals must be able to retrieve and manage information in an efficient, effective manner. The development of health technology and informatics (HTI) has been rapid, yet little is known about the knowledge and attitudes of nursing students with regard to using HTI. Therefore, the objective of the present study was to explore nursing students' knowledge of and attitudes toward using HTI and to use an e-learning workshop to enhance the effective use of HTI. In Phase I, 115 first-year full-time nursing students were invited to complete a 13-item questionnaire regarding knowledge of and attitudes toward computer and Internet use, knowledge of HTI, and attitudes toward the future development of HTI. Participants perceived themselves to be knowledgeable in computer and Internet use, while knowledge of HTI was perceived to be low and attitudes toward the future development of HTI were generally positive. Phase II was an e-learning HTI workshop; topics included an introduction to HTI, examples of HTI in use, and the application and implementation of various HTI projects. There were 30 participants in the E-learning workshop, and their feedback was positive. Nurses and all health care professionals must be prepared to participate in the development of health technology and informatics. Teaching and learning activities should be geared toward mastery of HTI in the nursing education curriculum in order to enhance health care quality and safety.     

Grouping inhibits motion fading by giving rise to virtual trackable features

After prolonged viewing of a slowly drifting or rotating pattern under strict fixation, the pattern appears to slow down and then momentarily stop. The authors show that grouping can slow down the process of "motion fading," suggesting that cortical configural form analysis interacts with the computation of motion signals during motion fading. The authors determined that grouping slows motion fading because it can give rise to trackable features, such as virtual contour terminators not present in the image, that possess stronger motion signals than would occur in the absence of such trackable features. That a continuously rotating stimulus will eventually be perceived to stop, despite the presence of such trackable features, suggests that the motion-from-form system itself can be fatigued. The finding that stationary form can remain visible even after the motion signal has faded suggests that the neural bases of motion visibility and form visibility arise from different neuronal populations.     

BOLD activation varies parametrically with corner angle throughout human retinotopic cortex

The Alternating Brightness Star (ABS) is an illusion that provides insight into the relationship between brightness perception and corner angle. Recent psychophysical studies of this illusion have shown that corner salience varies parametrically with corner angle, with sharp angles leading to strong illusory percepts and shallow angles leading to weak percepts. It is hypothesized that the illusory effects arise because of an interaction between surface corners and the shape of visual receptive fields: sharp surface corners may create hotspots of high local contrast due to processing by center-surround and other early receptive fields. If this hypothesis is correct, early visual neurons should respond powerfully to sharp corners and curved portions of surface edges. Indeed, the primary role of early visual neurons may be to localize the discontinuities along the edges of surfaces. If so, all early visual areas should show greater BOLD responses to sharp corners than to shallow corners. On the other hand, if corner processing is exclusively constrained to certain areas of the brain, only those specific areas will show greater responses to sharp vs shallow corners. To address this we explored the BOLD correlates of the ABS illusion in the human visual cortex using fMRI. We found that BOLD signal varies parametrically with corner angle throughout the visual cortex, offering the first neurophysiological correlates of the ABS illusion. This finding provides a neurophysiological basis for the previously reported psychophysical data that showed that corner salience varied parametrically with corner angle. We propose that all early visual areas localize discontinuities along the edges of surfaces, and that specific cortical corner-processing circuits further establish the specific nature of those discontinuities, such as their orientation.     

Attentional enhancement opposite a peripheral flash revealed using change blindness

We describe a new method for mapping spatial attentionthat reveals a pooling of attention in the hemifield opposite a peripheralflash. Our method exploits the fact that a brief full-field blank caninterfere with the detection of changes in a scene that occur during theblank. Attending to the location of a change, however, can overcome thischange blindness, so that changes are detected. The likelihood of detecting anew element in a scene therefore provides a measure of the occurrence ofattention at that element's location. Using this measure, we mappedhow attention changes in response to a task-irrelevant peripheral cue. Underconditions of visual fixation, change detection was above chance across theentire visual area tested. In addition, a "hot spot" ofattention (corresponding to near-perfect change detection) elongated alongthe cue-fixation axis, such that performance improved not only at the cuedlocation but also in the opposite hemifield.     

Processing of disyllabic compound words in Chinese aphasia: evidence for the processing limitations account

The current study addresses the debate between so-called 'structural' and 'processing limitation' accounts of aphasia, i.e., whether language impairments reflect the 'loss' of linguistic knowledge or its representations, or instead reflect a limitation in processing resources. Confrontation-naming task and category-judgment tasks were used to examine and compare the performance of non-fluent and fluent aphasics on different compound types of nouns and verbs. We demonstrate that aphasic patients' performance is modulated by the canonicity of the particular compound type, a result that holds true even for the category in which patients show a 'selective category deficit.' These findings weigh against the 'loss' of linguistic representations as the underlying cause of noun-verb deficits, instead supporting a 'processing limitations' approach.     

Flow Experiences Across Adulthood: Preliminary Findings on the Continuity Hypothesis

Flow experience is a psychological state characterized by simultaneous absorption, concentration, and enjoyment. Examining the change and continuity of the flow experience––an optimal state that contributes to well-being––is critical to the understanding of the lifelong trajectory of human flourishing. Nevertheless, to date there has been no systematic investigation of the relationship between age and flow experiences across adulthood. Developmental models of flow experiences suggest the continuity hypothesis that people are motivated to sustain a high level of flow experiences as long as conditions permit. We conducted two studies to investigate flow experiences among adults of different ages. Study 1 (N?=?1,162; age range 30–80) used longitudinal data from the Midlife in the United States (MIDUS) project, investigating the changes in flow experiences at work over a 10-year span. Study 2 (N?=?393; age range 20–82) was an online survey that examined age-related differences in flow experiences. Both studies revealed minimal relationships between age and flow experiences. Post-hoc analyses revealed no significant moderating effect of common demographics including gender, race, and education on the age–flow relationship. Taken together, these studies elucidate the “flow profile” in adulthood that is consistent with the continuity hypothesis. We discuss relations of the findings to the literature on flow experiences and well-being.