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1.  Grouping in object recognition: The role of a Gestalt law in letter identification 
Cognitive neuropsychology  2009;26(1):36-49.
The Gestalt psychologists reported a set of laws describing how vision groups elements to recognize objects. The Gestalt laws “prescribe for us what we are to recognize ‘as one thing’.” (Köhler, 1920). Were they right? Does object recognition involve grouping? Tests of the laws of grouping have been favorable, but mostly assessed only detection, not identification, of the compound object. The grouping of elements seen in the detection experiments with lattices and ‘snakes in the grass’ is compelling, but falls far short of the vivid everyday experience of recognizing a familiar, meaningful, named thing, which mediates the ordinary identification of an object. Thus, after nearly a century, there is hardly any evidence that grouping plays a role in ordinary object recognition. To assess grouping in object recognition, we made letters out of grating patches and measured threshold contrast for identifying these letters in visual noise as a function of perturbation of grating orientation, phase, and offset. We define a new measure, “wiggle,” to characterize the degree to which these various perturbations violate the Gestalt law of good continuation. We find that efficiency for letter identification is inversely proportional to wiggle, and is wholly determined by wiggle, independent of how the wiggle was produced. Thus the effects of three different kinds of shape perturbation on letter identifiability are predicted by a single measure of goodness of continuation. This shows that letter identification obeys the Gestalt law of good continuation, and may be the first confirmation of the original Gestalt claim that object recognition involves grouping.
PMCID: PMC2679997  PMID: 19424881
Gestalt; grouping; contour integration; good continuation; letter identification; object recognition; features; snake in the grass; snake letters; dot lattice
2.  The same binding in contour integration and crowding 
Journal of vision  2011;11(8):10.1167/11.8.10 10.
Binding of features helps object recognition in contour integration, but hinders it in crowding. In contour integration, aligned adjacent objects group together to form a path. In crowding, flanking objects make the target unidentifiable. But, to date, the two tasks have only been studied separately. May and Hess (2007) suggested that the same binding mediates both tasks. To test this idea, we ask observers to perform two different tasks with the same stimulus. We present oriented grating patches that form a “snake letter” in the periphery. Observers report either the identity of the whole letter (contour integration task) or the phase of one of the grating patches (crowding task). We manipulate the strength of binding between gratings by varying the alignment between them, i.e. the Gestalt goodness of continuation, measured as “wiggle”. We find that better alignment strengthens binding, which improves contour integration and worsens crowding. Observers show equal sensitivity to alignment in these two very different tasks, suggesting that the same binding mechanism underlies both phenomena. It has been claimed that grouping among flankers reduces their crowding of the target. Instead, we find that these published cases of weak crowding are due to weak binding resulting from target-flanker misalignment. We conclude that crowding is mediated solely by the grouping of flankers with the target and is independent of grouping among flankers.
PMCID: PMC3624759  PMID: 21757504
crowding; wiggle; grouping; binding; Gestalt; contour integration; good continuation; alignment; object recognition; snake letter
3.  A Century of Gestalt Psychology in Visual Perception I. Perceptual Grouping and Figure-Ground Organization 
Psychological bulletin  2012;138(6):1172-1217.
In 1912, Max Wertheimer published his paper on phi motion, widely recognized as the start of Gestalt psychology. Because of its continued relevance in modern psychology, this centennial anniversary is an excellent opportunity to take stock of what Gestalt psychology has offered and how it has changed since its inception. We first introduce the key findings and ideas in the Berlin school of Gestalt psychology, and then briefly sketch its development, rise, and fall. Next, we discuss its empirical and conceptual problems, and indicate how they are addressed in contemporary research on perceptual grouping and figure-ground organization. In particular, we review the principles of grouping, both classical (e.g., proximity, similarity, common fate, good continuation, closure, symmetry, parallelism) and new (e.g., synchrony, common region, element and uniform connectedness), and their role in contour integration and completion. We then review classic and new image-based principles of figure-ground organization, how it is influenced by past experience and attention, and how it relates to shape and depth perception. After an integrated review of the neural mechanisms involved in contour grouping, border-ownership, and figure-ground perception, we conclude by evaluating what modern vision science has offered compared to traditional Gestalt psychology, whether we can speak of a Gestalt revival, and where the remaining limitations and challenges lie. A better integration of this research tradition with the rest of vision science requires further progress regarding the conceptual and theoretical foundations of the Gestalt approach, which will be the focus of a second review paper.
PMCID: PMC3482144  PMID: 22845751
Gestalt; grouping principles; figure-ground organization; neural mechanisms; vision science
4.  Integrating Biological Motion: The Role of Grouping in the Perception of Point-Light Actions 
PLoS ONE  2011;6(10):e25867.
The human visual system is highly sensitive to biological motion and manages to organize even a highly reduced point-light stimulus into a vivid percept of human action. The current study investigated to what extent the origin of this saliency of point-light displays is related to its intrinsic Gestalt qualities. In particular, we studied whether biological motion perception is facilitated when the elements can be grouped according to good continuation and similarity as Gestalt principles of perceptual organization. We found that both grouping principles enhanced biological motion perception but their effects differed when stimuli were inverted. These results provide evidence that Gestalt principles of good continuity and similarity also apply to more complex and dynamic meaningful stimuli.
PMCID: PMC3185055  PMID: 21991376
5.  Bilateral Theta-Burst TMS to Influence Global Gestalt Perception 
PLoS ONE  2012;7(10):e47820.
While early and higher visual areas along the ventral visual pathway in the inferotemporal cortex are critical for the recognition of individual objects, the neural representation of human perception of complex global visual scenes remains under debate. Stroke patients with a selective deficit in the perception of a complex global Gestalt with intact recognition of individual objects – a deficit termed simultanagnosia – greatly helped to study this question. Interestingly, simultanagnosia typically results from bilateral lesions of the temporo-parietal junction (TPJ). The present study aimed to verify the relevance of this area for human global Gestalt perception. We applied continuous theta-burst TMS either unilaterally (left or right) or bilateral simultaneously over TPJ. Healthy subjects were presented with hierarchically organized visual stimuli that allowed parametrical degrading of the object at the global level. Identification of the global Gestalt was significantly modulated only for the bilateral TPJ stimulation condition. Our results strengthen the view that global Gestalt perception in the human brain involves TPJ and is co-dependent on both hemispheres.
PMCID: PMC3482242  PMID: 23110106
6.  A Century of Gestalt Psychology in Visual Perception II. Conceptual and Theoretical Foundations 
Psychological bulletin  2012;138(6):1218-1252.
Our first review paper on the occasion of the centennial anniversary of Gestalt psychology focused on perceptual grouping and figure-ground organization. It concluded that further progress requires a reconsideration of the conceptual and theoretical foundations of the Gestalt approach, which is provided here. In particular, we review contemporary formulations of holism within an information-processing framework, allowing for operational definitions (e.g., integral dimensions, emergent features, configural superiority, global precedence, primacy of holistic/configural properties) and a refined understanding of its psychological implications (e.g., at the level of attention, perception, and decision). We also review four lines of theoretical progress regarding the law of Prägnanz—the brain’s tendency of being attracted towards states corresponding to the simplest possible organization, given the available stimulation. The first considers the brain as a complex adaptive system and explains how self-organization solves the conundrum of trading between robustness and flexibility of perceptual states. The second specifies the economy principle in terms of optimization of neural resources, showing that elementary sensors working independently to minimize uncertainty can respond optimally at the system level. The third considers how Gestalt percepts (e.g., groups, objects) are optimal given the available stimulation, with optimality specified in Bayesian terms. Fourth, Structural Information Theory explains how a Gestaltist visual system that focuses on internal coding efficiency yields external veridicality as a side-effect. To answer the fundamental question of why things look as they do, a further synthesis of these complementary perspectives is required.
PMCID: PMC3728284  PMID: 22845750
Gestalt; holism; simplicity versus likelihood; dynamical systems; information theory
7.  Grouping by Proximity in Haptic Contour Detection 
PLoS ONE  2013;8(6):e65412.
We investigated the applicability of the Gestalt principle of perceptual grouping by proximity in the haptic modality. To do so, we investigated the influence of element proximity on haptic contour detection. In the course of four sessions ten participants performed a haptic contour detection task in which they freely explored a haptic random dot display that contained a contour in 50% of the trials. A contour was defined by a higher density of elements (raised dots), relative to the background surface. Proximity of the contour elements as well as the average proximity of background elements was systematically varied. We hypothesized that if proximity of contour elements influences haptic contour detection, detection will be more likely when contour elements are in closer proximity. This should be irrespective of the ratio with the proximity of the background elements. Results showed indeed that the closer the contour elements were, the higher the detection rates. Moreover, this was the case independent of the contour/background ratio. We conclude that the Gestalt law of proximity applies to haptic contour detection.
PMCID: PMC3676406  PMID: 23762364
8.  Learning to Identify Near-Acuity Letters, either with or without Flankers, Results in Improved Letter Size and Spacing Limits in Adults with Amblyopia 
PLoS ONE  2012;7(4):e35829.
Amblyopia is a developmental abnormality that results in deficits for a wide range of visual tasks, most notably, the reduced ability to see fine details, the loss in contrast sensitivity especially for small objects and the difficulty in seeing objects in clutter (crowding). The primary goal of this study was to evaluate whether crowding can be ameliorated in adults with amblyopia through perceptual learning using a flanked letter identification task that was designed to reduce crowding, and if so, whether the improvements transfer to untrained visual functions: visual acuity, contrast sensitivity and the size of visual span (the amount of information obtained in one fixation). To evaluate whether the improvements following this training task were specific to training with flankers, we also trained another group of adult observers with amblyopia using a single letter identification task that was designed to improve letter contrast sensitivity, not crowding. Following 10,000 trials of training, both groups of observers showed improvements in the respective training task. The improvements generalized to improved visual acuity, letter contrast sensitivity, size of the visual span, and reduced crowding. The magnitude of the improvement for each of these measurements was similar in the two training groups. Perceptual learning regimens aimed at reducing crowding or improving letter contrast sensitivity are both effective in improving visual acuity, contrast sensitivity for near-acuity objects and reducing the crowding effect, and could be useful as a clinical treatment for amblyopia.
PMCID: PMC3340394  PMID: 22558234
9.  Colony insularity through queen control on worker social motivation in ants. 
We investigated the relative contribution of the queen and workers to colony nestmate recognition cues and on colony insularity in the Carpenter ant Camponotus fellah. Workers were either individually isolated, preventing contact with both queen and workers (colonial deprived, CD), kept in queenless groups, allowing only worker-worker interactions (queen deprived, QD) or in queenright (QR) groups. Two weeks post-separation QD and QR workers were amicable towards each other but both rejected their CD nestmates, which suggests that the queen does not measurably influence the colony recognition cues. By contrast, aggression between QD and QR workers from the same original colony was apparent only after six months of separation. This clearly demonstrates the power of the Gestalt and indicates that the queen is not a dominant contributor to the nestmate recognition cues in this species. Aggression between nestmates was correlated with a greater hydrocarbon (HC) profile divergence for CD than for QD and QR workers, supporting the importance of worker-worker interactions in maintaining the colony Gestalt odour. While the queen does not significantly influence nestmate recognition cues, she does influence colony insularity since within 3 days QD (queenless for six months) workers from different colony origins merged to form a single queenless colony. By contrast, the corresponding QR colonies maintained their territoriality and did not merge. The originally divergent cuticular and postpharyngeal gland HC profiles became congruent following the merger. Therefore, while workers supply and blend the recognition signal, the queen affects worker-worker interaction by reducing social motivation and tolerance of alien conspecifics.
PMCID: PMC1691331  PMID: 12803913
10.  Defining the units of competition: Influences of perceptual organization on competitive interactions in human visual cortex 
Journal of cognitive neuroscience  2010;22(11):2417-2426.
Multiple stimuli that are present simultaneously in the visual field compete for neural representation. At the same time, however multiple stimuli in cluttered scenes also undergo perceptual organization according to certain rules originally defined by the Gestalt psychologists such as similarity or proximity, thereby segmenting scenes into candidate objects. How can these two seemingly orthogonal neural processes that occur early in the visual processing stream be reconciled? One possibility is that competition occurs among perceptual groups, rather than at the level of elements within a group. We probed this idea using fMRI by assessing competitive interactions across visual cortex in displays containing varying degrees of perceptual organization, or perceptual grouping (Grp). In strong Grp displays, elements were arranged such that either an illusory figure or a group of collinear elements were present, while in weak Grp displays the same elements were arranged randomly. Competitive interactions among stimuli were overcome throughout early visual cortex and V4, when elements were grouped regardless of Grp type. Our findings suggest that context-dependent grouping mechanisms and competitive interactions are linked to provide a bottom-up bias towards candidate objects in cluttered scenes.
PMCID: PMC2891594  PMID: 19925189
11.  Reductions in tobacco smoke pollution and increases in support for smoke‐free public places following the implementation of comprehensive smoke‐free workplace legislation in the Republic of Ireland: findings from the ITC Ireland/UK Survey 
Tobacco Control  2006;15(Suppl 3):iii51-iii58.
To evaluate the psychosocial and behavioural impact of the first ever national level comprehensive workplace smoke‐free law, implemented in Ireland in March 2004.
Quasi‐experimental prospective cohort survey: parallel cohort telephone surveys of national representative samples of adult smokers in Ireland (n  =  769) and the UK (n  =  416), surveyed before the law (December 2003 to January 2004) and 8–9 months after the law (December 2004 to January 2005).
Main outcome measures
Respondents' reports of smoking in key public venues, support for total bans in those key venues, and behavioural changes due to the law.
The Irish law led to dramatic declines in reported smoking in all venues, including workplaces (62% to 14%), restaurants (85% to 3%), and bars/pubs (98% to 5%). Support for total bans among Irish smokers increased in all venues, including workplaces (43% to 67%), restaurants (45% to 77%), and bars/pubs (13% to 46%). Overall, 83% of Irish smokers reported that the smoke‐free law was a “good” or “very good” thing. The proportion of Irish homes with smoking bans also increased. Approximately 46% of Irish smokers reported that the law had made them more likely to quit. Among Irish smokers who had quit at post‐legislation, 80% reported that the law had helped them quit and 88% reported that the law helped them stay quit.
The Ireland smoke‐free law stands as a positive example of how a population‐level policy intervention can achieve its public health goals while achieving a high level of acceptance among smokers. These findings support initiatives in many countries toward implementing smoke‐free legislation, particularly those who have ratified the Framework Convention on Tobacco Control, which calls for legislation to reduce tobacco smoke pollution.
PMCID: PMC2593063  PMID: 16754947
Framework Convention on Tobacco Control; FCTC; tobacco smoke pollution; environmental tobacco smoke; secondhand smoke; smoke‐free laws; tobacco control policy; policy evaluation
12.  An Evaluation of Graduated Driver Licensing Effects on Fatal Crash Involvements of Young Drivers in the United States 
Traffic injury prevention  2011;12(5):423-431.
Graduated driver licensing (GDL) systems are designed to reduce the high crash risk of young novice drivers. Almost all states in the United States have some form of a three-phased GDL system with various restrictions in the intermediate phase. Studies of the effects of GDL in various states show significant reductions in fatal crash involvements of 16- and 17-year-old drivers; however, only a few national studies of GDL effects have been published. The objective of this national panel study was to evaluate the effect of GDL laws on the fatal crash involvements of novice drivers while controlling for possible confounding factors not accounted for in prior studies.
The Fatality Analysis Reporting System (FARS) was used to examine 16- and 17-year-old driver involvement in fatal crashes (where GDL laws are applied) relative to two young driver age groups (19-20, 21-25) where GDL would not be expected to have an effect. Dates when various GDL laws were adopted in the states between 1990 and 2007 were coded from a variety of sources. Covariates in the longitudinal panel regression analyses conducted included four laws that could have an effect on 16- and 17-year-old drivers: primary enforcement seat belt laws, zero-tolerance (ZT) alcohol laws for drivers younger than age 21, lowering the blood alcohol concentration limit for driving to .08, and so-called “use and lose” laws where drivers aged 20 and younger lose their licenses for underage drinking violations.
The adoption of a GDL law of average strength was associated with a significant decrease in fatal crash involvements of 16- and 17-year-old drivers relative to fatal crash involvements of one of the two comparison groups. GDL laws rated as “good” showed stronger relationships to fatal crash reductions, and laws rated as “less than good” showed no reductions in crash involvements relative to the older driver comparison groups.
States that adopt a basic GDL law can expect a decrease of 8 to 14% in the proportion of 16- and 17-year-old drivers involved in fatal crashes (relative to 21- to 25-year-old drivers), depending upon their other existing laws that affect novice drivers, such as those used in these analyses. This finding is consistent with recent national studies that used different outcome measures and covariates. The results of this study provide additional support for states to adopt, maintain, and upgrade GDL systems to reduce youthful traffic crash fatalities.
PMCID: PMC3597244  PMID: 21972851
Graduated Driver Licensing (GDL); Fatality Analysis Reporting System (FARS); drivers aged 16-17; national panel study; regression analyses
13.  Higher-contrast requirements for recognizing low-pass–filtered letters 
Journal of Vision  2013;13(1):13.
Kwon and Legge (2011) found that high levels of letter recognition accuracy are possible even when letters are severely low-pass filtered (0.9 cycles per letter). How is letter recognition possible with such severe reduction in the spatial resolution of stimulus letters? Clues may come from understanding the possible interaction between contrast and spatial resolution in letter recognition. Here, we asked what the effect is on the contrast threshold for detecting and recognizing letters as the spatial-frequency cutoff of letters is reduced (in cycles per letter). We measured contrast thresholds of seven normally sighted subjects for detecting and recognizing single letters of the English alphabet. The letters were low-pass filtered with several cutoff frequencies (0.9–3.5 cycles per letter, including unfiltered letters). We found that differences in contrast thresholds between detection and recognition increased substantially with decreasing cutoff frequency. We also incorporated the human contrast sensitivity function into an ideal observer model and found qualitatively good agreement between the pattern of performance for the model and our human subjects. Our findings show that the human visual system requires higher contrast for letter recognition when spatial resolution is severely limited. Good agreement between the model and human subjects shows that the greater contrast requirement for recognizing low-pass letters is due to a reduction in the information content of the letters rather than a change in human visual processing. The reduction in stimulus information may be due to increasing stimulus similarity associated with a reduction in spatial-frequency cutoff.
PMCID: PMC3586998  PMID: 23302216
letter recognition; spatial resolution; contrast; spatial-frequency bandwidth; peripheral vision; critical bandwidth; ideal observer; contrast sensitivity function; letter similarity
14.  Averaging facial expression over time 
Journal of vision  2009;9(11):1.1-113.
The visual system groups similar features, objects, and motion (e.g., Gestalt grouping). Recent work suggests that the computation underlying perceptual grouping may be one of summary statistical representation. Summary representation occurs for low-level features, such as size, motion, and position, and even for high level stimuli, including faces; for example, observers accurately perceive the average expression in a group of faces (J. Haberman & D. Whitney, 2007, 2009). The purpose of the present experiments was to characterize the time-course of this facial integration mechanism. In a series of three experiments, we measured observers’ abilities to recognize the average expression of a temporal sequence of distinct faces. Faces were presented in sets of 4, 12, or 20, at temporal frequencies ranging from 1.6 to 21.3 Hz. The results revealed that observers perceived the average expression in a temporal sequence of different faces as precisely as they perceived a single face presented repeatedly. The facial averaging was independent of temporal frequency or set size, but depended on the total duration of exposed faces, with a time constant of ~800 ms. These experiments provide evidence that the visual system is sensitive to the ensemble characteristics of complex objects presented over time.
PMCID: PMC2857387  PMID: 20053064
vision; perception; face; object recognition; temporal integration; texture; spatial vision
15.  Top-Down Control in Contour Grouping 
PLoS ONE  2013;8(1):e54085.
Human observers tend to group oriented line segments into full contours if they follow the Gestalt rule of 'good continuation'. It is commonly assumed that contour grouping emerges automatically in early visual cortex. In contrast, recent work in animal models suggests that contour grouping requires learning and thus involves top-down control from higher brain structures. Here we explore mechanisms of top-down control in perceptual grouping by investigating synchronicity within EEG oscillations. Human participants saw two micro-Gabor arrays in a random order, with the task to indicate whether the first (S1) or the second stimulus (S2) contained a contour of collinearly aligned elements. Contour compared to non-contour S1 produced a larger posterior post-stimulus beta power (15–21 Hz). Contour S2 was associated with a pre-stimulus decrease in posterior alpha power (11–12 Hz) and in fronto-posterior theta (4–5 Hz) phase couplings, but not with a post-stimulus increase in beta power. The results indicate that subjects used prior knowledge from S1 processing for S2 contour grouping. Expanding previous work on theta oscillations, we propose that long-range theta synchrony shapes neural responses to perceptual groupings regulating lateral inhibition in early visual cortex.
PMCID: PMC3542329  PMID: 23326575
16.  Effect of Orthographic Processes on Letter Identity and Letter-Position Encoding in Dyslexic Children 
The ability to identify letters and encode their position is a crucial step of the word recognition process. However and despite their word identification problem, the ability of dyslexic children to encode letter identity and letter-position within strings was not systematically investigated. This study aimed at filling this gap and further explored how letter identity and letter-position encoding is modulated by letter context in developmental dyslexia. For this purpose, a letter-string comparison task was administered to French dyslexic children and two chronological age (CA) and reading age (RA)-matched control groups. Children had to judge whether two successively and briefly presented four-letter strings were identical or different. Letter-position and letter identity were manipulated through the transposition (e.g., RTGM vs. RMGT) or substitution of two letters (e.g., TSHF vs. TGHD). Non-words, pseudo-words, and words were used as stimuli to investigate sub-lexical and lexical effects on letter encoding. Dyslexic children showed both substitution and transposition detection problems relative to CA-controls. A substitution advantage over transpositions was only found for words in dyslexic children whereas it extended to pseudo-words in RA-controls and to all type of items in CA-controls. Letters were better identified in the dyslexic group when belonging to orthographically familiar strings. Letter-position encoding was very impaired in dyslexic children who did not show any word context effect in contrast to CA-controls. Overall, the current findings point to a strong letter identity and letter-position encoding disorder in developmental dyslexia.
PMCID: PMC3356879  PMID: 22661961
letter-string processing; letter-position encoding; letter-identity encoding; letter transposition; letter substitution; reading acquisition; dyslexic children
17.  The influence of reading expertise in mirror-letter perception: Evidence from beginning and expert readers 
The visual word recognition system recruits neuronal systems originally developed for object perception which are characterized by orientation insensitivity to mirror reversals. It has been proposed that during reading acquisition beginning readers have to “unlearn” this natural tolerance to mirror reversals in order to efficiently discriminate letters and words. Therefore, it is supposed that this unlearning process takes place in a gradual way and that reading expertise modulates mirror-letter discrimination. However, to date no supporting evidence for this has been obtained. We present data from an eye-movement study that investigated the degree of sensitivity to mirror-letters in a group of beginning readers and a group of expert readers. Participants had to decide which of the two strings presented on a screen corresponded to an auditorily presented word. Visual displays always included the correct target word and one distractor word. Results showed that those distractors that were the same as the target word except for the mirror lateralization of two internal letters attracted participants’ attention more than distractors created by replacement of two internal letters. Interestingly, the time course of the effects was found to be different for the two groups, with beginning readers showing a greater tolerance (decreased sensitivity) to mirror-letters than expert readers. Implications of these findings are discussed within the framework of preceding evidence showing how reading expertise modulates letter identification.
PMCID: PMC3836404  PMID: 24273596
18.  Autistic autobiography 
Autism narratives are not just stories or histories, describing a given reality. They are creating the language in which to describe the experience of autism, and hence helping to forge the concepts in which to think autism. This paper focuses on a series of autobiographies that began with Grandin's Emergence. These are often said to show us autism from the ‘inside’. The paper proposes that instead they are developing ways to describe experience for which there is little pre-existing language. Wittgenstein has many well-known aphorisms about how we understand other people directly, without inference. They condense what he had found in Wolfgang Köhler's Gestalt Psychology. These phenomena of direct understanding what other people are doing are, Köhler wrote, ‘the common property and practice of mankind'. They are not the common property and practice of people with autism. Ordinary language is rich in age-old ways to describe what others are thinking, feeling and so forth. Köhler's phenomena are the bedrock on which such language rests. There is no such discourse for autism, because Köhler's phenomena are absent. But a new discourse is being made up right now, i.e. ways of talking for which the autobiographies serve as working prototypes.
PMCID: PMC2677587  PMID: 19528032
Köhler; Wittgenstein; Grandin; Donna Williams; Mukhopadhyay; Tammet
19.  Structured Printed Referral Letter (Form Letter); Saves Time and Improves Communication 
Referral of patients to hospitals, specialists and other institutions is an essential part of primary health care. Patients are referred to specialists when investigation or therapeutic options are exhausted in primary care or when opinion or advice is needed from them. Referral has considerable implications for patients, health care system and health care costs. Good communication between primary and secondary care is essential for the smooth running of any health care system. Referral and reply letters are the sole means of communication between doctors most of the time and breakdown in communication could lead to poor continuity of care, delayed diagnoses, polypharmacy, increased litigation risk and unnecessary testing. A referral letter also helps to avoid patient dissatisfaction and loss of confidence in family physician. Studies of referral letters have reported that specialists are dissatisfied with their quality and content. Inclusion of letter writing skills in the medical curriculum, peer assessment and feedback have shown to improve the quality of referral letters. Form letters have shown to enhance information content and communication in referral process. In Sri Lanka referral letters are usually hand written and frequent complaints are that these letters do not contain adequate information and retrieval of information is a problem due to poor legibility and clarity. Sometimes Primary care doctors refer patients to hospitals and specialists with only verbal instructions. To address these short comings this form letter was introduced. Based on the guidelines and systematic review of published articles, items of information to be included were decided. Printed forms of the letter are kept in the practice and the doctor has to just fill up relevant information under each heading. The objectives of introducing this structured referral letter was to improve the quality and standard of referral letters and save time for both general practitioners and specialists.
PMCID: PMC3894031  PMID: 24479068
Referral letters; communications between GP and specialist; structured referral forms; general practice
20.  A double dissociation of the acuity and crowding limits to letter identification, and the promise of improved visual screening 
Journal of Vision  2014;14(5):3.
Here, we systematically explore the size and spacing requirements for identifying a letter among other letters. We measure acuity for flanked and unflanked letters, centrally and peripherally, in normals and amblyopes. We find that acuity, overlap masking, and crowding each demand a minimum size or spacing for readable text. Just measuring flanked and unflanked acuity is enough for our proposed model to predict the observer's threshold size and spacing for letters at any eccentricity.
We also find that amblyopia in adults retains the character of the childhood condition that caused it. Amblyopia is a developmental neural deficit that can occur as a result of either strabismus or anisometropia in childhood. Peripheral viewing during childhood due to strabismus results in amblyopia that is crowding limited, like peripheral vision. Optical blur of one eye during childhood due to anisometropia without strabismus results in amblyopia that is acuity limited, like blurred vision. Furthermore, we find that the spacing:acuity ratio of flanked and unflanked acuity can distinguish strabismic amblyopia from purely anisometropic amblyopia in nearly perfect agreement with lack of stereopsis. A scatter diagram of threshold spacing versus acuity, one point per patient, for several diagnostic groups, reveals the diagnostic power of flanked acuity testing. These results and two demonstrations indicate that the sensitivity of visual screening tests can be improved by using flankers that are more tightly spaced and letter like.
Finally, in concert with Strappini, Pelli, Di Pace, and Martelli (submitted), we jointly report a double dissociation between acuity and crowding. Two clinical conditions—anisometropic amblyopia and apperceptive agnosia—each selectively impair either acuity A or the spacing:acuity ratio S/A, not both. Furthermore, when we specifically estimate crowding, we find a double dissociation between acuity and crowding. Models of human object recognition will need to accommodate this newly discovered independence of acuity and crowding.
PMCID: PMC4021854  PMID: 24799622
amblyopia; crowding; strabismic; anisometropic; acuity; screening; spacing:acuity ratio; critical spacing; threshold spacing; legibility; overlap masking; letter identification; object recognition
21.  Overt use of a tactile-kinesthetic strategy shifts to covert processing in rehabilitation of letter-by-letter reading 
Aphasiology  2010;24(11):1424-1442.
Letter-by-letter readers identify each letter of the word they are reading serially in left to right order before recognizing the word. When their letter naming is also impaired, letter-by-letter reading is inaccurate and can render even single word reading very poor. Tactile and/or kinesthetic strategies have been reported to improve reading in these patients, but only under certain conditions or for a limited set of stimuli.
The primary aim of the current study was to determine whether a tactile/kinesthetic treatment could significantly improve reading specifically under normal reading conditions, i.e. reading untrained words presented in free vision and read without overt use of the strategy.
Methods & Procedures
Three chronic letter-by-letter readers participated in a tactile/kinesthetic treatment aimed at first improving letter naming accuracy (phase 1) and then letter-by-letter reading speed (phase 2). In a multiple case series design, accuracy and speed of reading untrained words without overt use of the trained tactile/kinesthetic strategy was assessed before phase 1, after phase 1 and again after phase 2.
Outcomes & Results
All three patients significantly improved both their speed and accuracy reading untrained words without overt use of the trained tactile/kinesthetic strategy. All three patients required the additional practice in phase 2 to achieve significant improvement. Treatment did not target sentence level reading, yet two of the three patients became so adept that they could read entire sentences.
This study replicates previous findings on the efficacy of tactile/kinesthetic treatment for letter-by-letter readers with poor letter naming. It further demonstrates that this treatment can alter cognitive processing such that words never specifically trained can be read in free vision without overtly using the trained strategy. The data suggest that an important element in achieving this level of generalization is continuing training beyond the point of initial mastery (i.e. accurate letter naming).
PMCID: PMC3002229  PMID: 21170161
aphasia; cognitive rehabilitation; Speech-Language Pathology; pure alexia; letter-by-letter reading; generalization
22.  Neuropsychological Assessment of Adult Patients with Shunted Hydrocephalus 
This study is planned to determine the neurocognitive difficulties of hydrocephalic adults.
The research group contained healthy adults (control group, n : 15), and hydrocephalic adults (n : 15). Hydrocephalic group consisted of patients with idiopathic aquaduct stenosis and post-meningitis hydrocephalus. All patients were followed with shunted hydrocephalus and not gone to shunt revision during last two years. They were chosen from either asymptomatic or had only minor symptoms without motor and sensorineural deficit. A neuropsychological test battery (Raven Standart Progressive Matrices, Bender-Gestalt Test, Cancellation Test, Clock Drawing Test, Facial Recognition Test, Line Orientation Test, Serial Digit Learning Test, Stroop Color Word Interference Test-TBAG Form, Verbal Fluency Test, Verbal Fluency Test, Visual-Aural Digit Span Test-B) was applied to all groups.
Neuropsychological assessment of hydrocephalic patients demonstrated that they had poor performance on visual, semantic and working memory, visuoconstructive and frontal functions, reading, attention, motor coordination and executive function of parietal lobe which related with complex and perseverative behaviour. Eventually, these patients had significant impairment on the neurocognitive functions of their frontal, parietal and temporal lobes. On the other hand, the statistical analyses performed on demographic data showed that the aetiology of the hydrocephalus, age, sex and localization of the shunt (frontal or posterior parietal) did not affect the test results.
This prospective study showed that adult patients with hydrocephalus have serious neuropsychological problems which might be directly caused by the hydrocephalus; and these problems may cause serious adaptive difficulties in their social, cultural, behavioral and academic life.
PMCID: PMC2851080  PMID: 20379471
Adult; Hydrocephalus; Neuropsychological assessment
23.  Women’s views on reminder letters for screening mammography 
Canadian Family Physician  2009;55(6):622-623.e4.
To explore women’s perspectives on the acceptability and content of reminder letters for screening mammography from their family physicians, as well as such letters’ effect on screening intentions.
Cross-sectional mailed survey followed by focus groups with a subgroup of respondents.
One family physician was randomly selected from each of 23 family health networks and primary care networks participating in a demonstration project to increase the delivery of preventive services. From the practice roster of each physician, up to 35 randomly selected women aged 50 to 69 years who were due or overdue for screening mammograms and who had received reminder letters from their family physicians within the past 6 months were surveyed.
Recall of having received reminder letters and of their content, influence of the letters on decisions to have mammograms, and interest in receiving future reminder letters. Focus group interviews with survey respondents explored the survey findings in greater depth using a standardized interview guide.
The response rate to the survey was 55.7% (384 of 689), and 45.1% (173 of 384) of responding women reported having mammograms in the past 6 months. Among women who recalled receiving letters and either making appointments for or having mammograms, 74.8% (122 of 163) indicated that the letters substantially influenced their decisions. Most respondents (77.1% [296 of 384]) indicated that they would like to continue to receive reminders, and 28.9% (111 of 384) indicated that they would like to receive additional information about mammograms. Participants in 2 focus groups (n = 3 and n = 5) indicated that they thought letters reflected a positive attitude of physicians toward mammography screening. They also commented that newly eligible women had different information needs than women who had had mammograms done in the past.
Reminder letters were considered by participants to be useful and appeared to influence women’s decisions to undergo mammography screening.
PMCID: PMC2694090  PMID: 19509209
24.  The development of individuation in autism 
Evidence suggests that people with autism use holistic information differently than typical adults. The current studies examine this possibility by investigating how core visual processes that contribute to holistic processing – individuation and element grouping – develop in participants with autism and typically developing (TD) participants matched for age, IQ and gender. Individuation refers to the ability to `see' up to 4 elements simultaneously; grouping these elements can change the number of elements that are rapidly apprehended. We examined these core processes using two well-established paradigms, rapid enumeration and multiple object tracking (MOT). In both tasks, a performance limit of about 4 elements in adulthood is thought to reflect individuation capacity. Participants with autism has a smaller individuation capacity than TD controls, regardless of whether they were enumerating static elements or tracking moving ones. To manipulate holistic information and individuation performance, we grouped the elements into a design or had elements move together. Participants with autism were affected to a similar degree as TD participants by the holistic information, whether the manipulation helped or hurt performance, consistent with evidence that some types of gestalt/grouping information are processed typically in autism. There was substantial development in autism from childhood to adolescence, but not from adolescence to adulthood, a pattern distinct from TD participants. These results provide important information about core visual processes in autism, as well as insight into the architecture of vision (e.g., individuation appears distinct from visual strengths in autism, such as visual search, despite similarities).
PMCID: PMC3608798  PMID: 22963232
autism; subitizing; global-local; individuation; holistic; configural; grouping; gestalt; indexing
25.  Strong advocacy led to successful implementation of smokefree Mexico City 
Tobacco control  2010;20(1):64-72.
To describe the approval process and implementation of the 100% smokefree law in Mexico City and a competing federal law between 2007 and 2010.
Reviewed smokefree legislation, published newspaper articles and interviewed key informants.
Strong efforts by tobacco control advocacy groups and key policymakers in Mexico City in 2008 prompted the approval of a 100% smokefree law following the WHO FCTC. As elsewhere, the tobacco industry utilised the hospitality sector to block smokefree legislation, challenged the City law before the Supreme Court and promoted the passage of a federal law that required designated smoking areas. These tactics disrupted implementation of the City law by causing confusion over which law applied in Mexico City. Despite interference, the City law increased public support for 100% smokefree policies and decreased the social acceptability of smoking. In September 2009, the Supreme Court ruled in favour of the City law, giving it the authority to go beyond the federal law to protect the fundamental right of health for all citizens.
Early education and enforcement efforts by tobacco control advocates promoted the City law in 2008 but advocates should still anticipate continuing opposition from the tobacco industry, which will require continued pressure on the government. Advocates should utilise the Supreme Court’s ruling to promote 100% smokefree policies outside Mexico City. Strong advocacy for the City law could be used as a model of success throughout Mexico and other Latin American countries.
PMCID: PMC3089444  PMID: 21059606

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