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1.
J Adolesc ; 96(4): 771-788, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38287896

ABSTRACT

INTRODUCTION: College transition is often regarded as the most stressful phase of life by college students. Hence, it is necessary to find ways to help them adjust more smoothly to this transition. Hope, as conceptualized by C. R. Snyder, has been widely studied as a predictor of optimal functioning and has been shown to be associated with better adjustment among college students. This study aimed to shed light on the role of hope in college transition by examining its unique reciprocal relationships with an array of important psychosocial resources and emotional well-being among first-year college students. METHODS: Data were collected from a sample of Hong Kong college freshmen (N = 433, Medianage = 18 years old, 63.7% female) at two time points. At each time point, participants completed self-reported measures tapping into their levels of hope, psychosocial resources, and emotional well-being. Psychological resources included general and academic self-efficacy, meaning in life, and optimism. Social resources included secure attachment, perceived school environment, and social support. Emotional well-being was operationalized as positive and negative emotions. Cross-lagged panel models were constructed and tested by path analyses. RESULTS: When autoregression and the effects of other variables were controlled, a greater sense of hope uniquely predicted higher levels of general and academic self-efficacy, greater presence of life meanings, more secure attachment, and more positive and fewer negative emotions. On the other hand, higher levels of meaning in life (both presence and search) and social support uniquely predicted greater hope. Academic hope and presence of life meanings reciprocally predicted one another, whereas other significant cross-lagged relationships were unidirectional. CONCLUSIONS: The findings suggest interventions that promote hope can be useful in helping college freshmen adjust to the new college environment by enhancing their psychosocial resources and emotional well-being. Such interventions would be more effective if they included elements that boost meaning in life and social support, which are expected to further enhance the perceptions of hope.


Subject(s)
Hope , Social Support , Students , Humans , Female , Students/psychology , Male , Adolescent , Universities , Hong Kong , Young Adult , Self Efficacy , Emotions , Adaptation, Psychological
2.
Behav Res Methods ; 2023 Oct 05.
Article in English | MEDLINE | ID: mdl-37798596

ABSTRACT

Mediation, moderation, and moderated mediation are common in behavioral research models. Several tools are available for estimating indirect effects, conditional effects, and conditional indirect effects and forming their confidence intervals. However, there are no simple-to-use tools that can appropriately form the bootstrapping confidence interval for standardized conditional indirect effects. Moreover, some tools are restricted to a limited type of models. We developed an R package, manymome, which can be used to estimate and form confidence intervals for indirect effects, conditional effects, and conditional indirect effects, standardized or not, using a two-step approach: model parameters are estimated either by structural equation modeling using lavaan or by a set of linear regression models using lm, and then the coefficients are used to compute the requested effects and form confidence intervals. It can be used when there are missing data if the model is fitted by structural equation modeling. There are only a few limitations on some aspects of a model, and no inherent limitations on the number of predictors, the number of independent variables, or the number of moderators and mediators. The goal is to have a tool that allows researchers to focus on model fitting first and worry about estimating the effects later. The use of the model is illustrated using a few numerical examples, and the limitations of the package are discussed.

3.
Article in English | MEDLINE | ID: mdl-37444072

ABSTRACT

Social unrest, coupled with the outbreak of COVID-19, was a double-hit for Hong Kong in early 2020. Those stressful societal situations not only trigger negative emotions, such as anxiety and/or depression, but also consolidate a person's belief towards oneself (i.e., meaning in life) and society (i.e., social axioms). The study included 2031 participants from the Formation and Transformation of Beliefs in Chinese (FTBC) project dataset. The data were collected in Hong Kong from February 2020 to March 2020 (double-hit). Path analysis and multiple regression were used to examine the mediating and moderating effects of the presence subscale (P) of the Meaning in Life Questionnaire (MLQ) on the relations between social axioms and negative emotions. Results showed that low MLQ-P mediated the associations between cynicism and negative emotions and between low religiosity and negative emotions and moderated the relation between social cynicism and emotional outcomes. Exploratory analyses showed that MLQ-Search (S) mediated the relations between reward for application and negative emotions, between social complexity and negative emotions, and between fate control and negative emotions, and moderated the relation between religiosity and stress. As far as we know, this study reported the first evidence of the role of meaning in life in explaining and modifying the associations between social axioms and mood states. The presence of and search for meaning in life seem to work differently with respect to the relations between social axioms and negative emotions, with important implications for understanding the dynamics of social and personal beliefs in affecting mental health in times of large-scale public crisis.


Subject(s)
COVID-19 , Humans , Hong Kong/epidemiology , COVID-19/epidemiology , Emotions , Anxiety , Mental Health
4.
Br J Psychol ; 114(4): 945-968, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37309918

ABSTRACT

We investigated the relationship between ambient temperature and prosocial behaviour in real-life settings. It was guided by two mechanisms of opposite predictions, namely (1) higher temperatures decrease prosociality by harming well-being, and (2) higher temperatures increase prosociality by promoting the embodied cognition of social warmth. In Study 1, U.S. state-level time-series data (2002-2015) supported the first mechanism, with higher temperatures predicting lower volunteer rates through lower well-being. Study 2 furthered the investigation by probing the relationship between neighbourhood temperature and civic engagement of 2268 U.S. citizens. The data partially supported the well-being mechanism and reported findings contradictory to the social embodiment mechanism. Higher temperatures predicted lower interpersonal trust and subsequently lower civic engagement. The unexpected finding hinted at a cognitive effect of heat and a compensatory mechanism in social thermoregulation. We discussed the findings regarding their methodological strengths and weaknesses, with cautions made on ecological fallacies and alternative models.


Subject(s)
Altruism , Volunteers , Humans , Temperature , Volunteers/psychology
5.
Soc Sci Med ; 321: 115774, 2023 03.
Article in English | MEDLINE | ID: mdl-36796169

ABSTRACT

OBJECTIVE: The current study aimed to examine the latent heterogeneity of gaming and social withdrawal behaviors in internet gamers and their associations with help-seeking behaviors. METHOD: The present study recruited 3430 young people (1874 adolescents and 1556 young adults) in Hong Kong in 2019. The participants completed the Internet Gaming Disorder (IGD) Scale, Hikikomori Questionnaire, and measures on gaming characteristics, depression, help-seeking, and suicidality. Factor mixture analysis was used to classify the participants into latent classes based on their latent factors of IGD and hikikomori in separate age groups. Latent class regressions examined the associations between help-seeking and suicidality. RESULTS: Both adolescents and young adults supported a 4-class, 2-factor model on gaming and social withdrawal behaviors. Over two-third of the sample were classified as healthy or low-risk gamers with low IGD factor means and low prevalence of hikikomori. Around one-fourth was moderate-risk gamers with elevated prevalence of hikikomori, higher IGD symptoms and psychological distress. A minority of the sample (3.8%-5.8%) belonged to high-risk gamers with the highest IGD symptoms and prevalence of hikikomori and heightened suicidal risks. Help-seeking in low-risk and moderate-risk gamers was positively associated with depressive symptoms and negatively associated with suicidal ideation. Perceived usefulness of help-seeking was significantly linked with lower likelihoods of suicidal ideation in the moderate-risk gamers and suicide attempt in the high-risk gamers. CONCLUSIONS: The present findings explicate the latent heterogeneity of gaming and social withdrawal behaviors and associated factors on help-seeking and suicidality among internet gamers in Hong Kong.


Subject(s)
Behavior, Addictive , Phobia, Social , Video Games , Humans , Young Adult , Adolescent , Hong Kong/epidemiology , Video Games/psychology , Social Isolation , Internet , Behavior, Addictive/epidemiology , Behavior, Addictive/psychology
6.
Health Psychol ; 41(7): 502-505, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35467898

ABSTRACT

Moderation effects in multiple regression, tested usually by the inclusion of a product term, are frequently investigated in health psychology. However, several issues in presenting the moderation effects in standardized units and their associated confidence intervals are commonly observed. While an old method had been proposed to standardize variables in moderated regression before fitting a moderated regression model, this method was rarely used due to inconvenience and even when used, the confidence intervals derived were biased. Here, we attempt to solve these two problems by providing a tool to conveniently conduct standardization in moderated regression without the step of standardizing the variables beforehand and to accurately form the nonparametric bootstrapping confidence intervals for this standardized measure of moderation effects. Health psychology researchers are now equipped with a tool that can be used to report and interpret standardized moderation effects correctly. (PsycInfo Database Record (c) 2022 APA, all rights reserved).


Subject(s)
Behavioral Medicine , Research Design , Humans
7.
Sleep Health ; 7(3): 384-389, 2021 06.
Article in English | MEDLINE | ID: mdl-33935014

ABSTRACT

OBJECTIVE: Dispositional characteristics like emotional stability and social cynicism have been consistently associated with negative affect, which is a known predictor and outcome of poor sleep quality. This study hypothesized a bidirectional relationship of sleep quality with emotional stability and social cynicism over a five-year period. METHODS: Participants were 7,181 Chinese people, who completed two waves of online surveys from a larger panel study. Questionnaires on Big Five personality traits, social cynicism, and sleep quality were administered twice at a five-year interval. RESULTS: Cross-lagged analysis revealed a significant bidirectional relationship between emotional stability and sleep quality over five years as hypothesized. However, there was no association between sleep quality and social cynicism in either direction. CONCLUSION: Our study provides consistent evidence of a bidirectional relationship between sleep quality and emotional stability in a five-year time-frame among a younger population (mean age = 24.86). Given the critical role of emotional stability in various areas of functioning, the findings highlight the importance of sleep health education in young adults, who are going through a critical period of personality development.


Subject(s)
Emotions , Sleep Quality , Adult , Humans , Personality , Sleep , Surveys and Questionnaires , Young Adult
8.
Front Psychol ; 11: 142, 2020.
Article in English | MEDLINE | ID: mdl-32116943

ABSTRACT

Implicit theories have been widely studied in different domains; however, it is still debatable whether these theories are domain-specific or domain-general. Using the Implicit Theories Scale (ITS) about six fundamental psychological attributes, i.e., intelligence, personality, cognition, feeling, behavior, and emotion, we examined domain specificity versus generality using a factor analytic approach; in addition, we investigated associations between implicit theories about these domains and related psychological attributes. In four sequential studies, we translated a Chinese version of the ITS (Study 1), tested inter-item correlations within and between subscales (Studies 1-4), and conducted exploratory factor analysis (Studies 2 and 3) and confirmatory factor analysis (Studies 3 and 4). We tested associations between implicit theory domains and coping, resilience, grit, and school performance (Studies 3 and 4). Results showed that the six ITS subscales were independent, while the implicit theories about cognition, feeling, behavior, and emotion shared a common component. The implicit theories of intelligence and personality were independent and did not share a common component. The six domains presented different patterns of association with psychological variables. Overall, our results suggest that implicit theories are both domain-specific and domain-general. Future studies are needed to examine the mechanism underlying the domain specificity and generality of implicit theories.

9.
Article in English | MEDLINE | ID: mdl-30061459

ABSTRACT

Do we perceive fine details in the visual periphery? Here, we propose that phenomenology in the visual periphery can be characterized by an inflated sense of perceptual capacity, as observers overestimate the quality of their perceptual inputs. Distinct from the well-known perceptual phenomenon of 'filling-in' where perceptual content is generated or completed endogenously, inflation can be characterized by incorrect introspection at the subjective level. The perceptual content itself may be absent or weak (i.e. not necessarily filled-in), and yet such content is mistakenly regarded by the system as rich. Behaviourally, this can be reflected by metacognitive deficits in the degree to which confidence judgements track task accuracy, and decisional biases for observers to think particular items are present, even when they are not. In two experiments using paradigms that exploit unique attributes of peripheral vision (crowding and summary statistics), we provide evidence that both types of deficits are present in peripheral vision, as observers' reports are marked by overconfidence in discrimination judgements and high numbers of false alarms in detection judgements. We discuss potential mechanisms that may be the cause of inflation and propose future experiments to further explore this unique sensory phenomenon.This article is part of the theme issue 'Perceptual consciousness and cognitive access'.


Subject(s)
Consciousness , Metacognition , Vision, Ocular , Visual Perception , Adult , Female , Hong Kong , Humans , Judgment , Male , Photic Stimulation , Psychophysics , Young Adult
10.
J Vis ; 17(11): 14, 2017 09 01.
Article in English | MEDLINE | ID: mdl-28973567

ABSTRACT

Crowding impedes the identification of flanked objects in peripheral vision. Prior studies have shown crowding strength decreases with target-flanker similarity. Research on crowding in Chinese-character recognition has been scarce in the literature. We aimed to fill the research gap by examining the effects of structural similarity on Chinese-character crowding. Regularity in within-character configuration, i.e., orthographic legality, of flankers was manipulated in Experiment 1. Target-flanker similarity in orthographic legality did not affect crowding strength, measured as contrast threshold elevation. Crowding weakened only when the strokes in the flankers were scrambled. Contour integrity of flankers was manipulated by randomly perturbing the phase spectra of the stimulus images in Experiments 2a and 2b. Crowding by perturbed-phase flankers remained robust but was weaker compared with intact-phase flankers. Target-flanker similarity in contour integrity modulated crowding strength. Our findings were consistent with the postulation that faulty integration of low-level visual features contributed to crowding of Chinese characters. Studies on Chinese-character recognition and crowding can provide important insights into how the visual system processes complex daily objects.


Subject(s)
Form Perception/physiology , Pattern Recognition, Visual/physiology , Psychometrics/methods , Visual Perception/physiology , Writing , China , Discrimination, Psychological , Humans , Male , Psychophysics/methods
11.
Invest Ophthalmol Vis Sci ; 57(8): 3836-43, 2016 Jul 01.
Article in English | MEDLINE | ID: mdl-27442222

ABSTRACT

PURPOSE: The continuous-text reading-acuity test MNREAD is designed to measure the reading performance of people with normal and low vision. This test is used to estimate maximum reading speed (MRS), critical print size (CPS), reading acuity (RA), and the reading accessibility index (ACC). Here we report the age dependence of these measures for normally sighted individuals, providing baseline data for MNREAD testing. METHODS: We analyzed MNREAD data from 645 normally sighted participants ranging in age from 8 to 81 years. The data were collected in several studies conducted by different testers and at different sites in our research program, enabling evaluation of robustness of the test. RESULTS: Maximum reading speed and reading accessibility index showed a trilinear dependence on age: first increasing from 8 to 16 years (MRS: 140-200 words per minute [wpm]; ACC: 0.7-1.0); then stabilizing in the range of 16 to 40 years (MRS: 200 ± 25 wpm; ACC: 1.0 ± 0.14); and decreasing to 175 wpm and 0.88 by 81 years. Critical print size was constant from 8 to 23 years (0.08 logMAR), increased slowly until 68 years (0.21 logMAR), and then more rapidly until 81 years (0.34 logMAR). logMAR reading acuity improved from -0.1 at 8 years to -0.18 at 16 years, then gradually worsened to -0.05 at 81 years. CONCLUSIONS: We found a weak dependence of the MNREAD parameters on age in normal vision. In broad terms, MNREAD performance exhibits differences between three age groups: children 8 to 16 years, young adults 16 to 40 years, and middle-aged to older adults >40 years.


Subject(s)
Reading , Vision, Ocular/physiology , Adolescent , Adult , Aged , Aged, 80 and over , Aging/physiology , Child , Contrast Sensitivity/physiology , Female , Humans , Male , Middle Aged , Sex Characteristics , Vision Tests , Young Adult
12.
Cogn Neurosci ; 5(3-4): 160-7, 2014.
Article in English | MEDLINE | ID: mdl-24784503

ABSTRACT

We investigated how face-selective cortical areas process configural and componential face information and how race of faces may influence these processes. Participants saw blurred (preserving configural information), scrambled (preserving componential information), and whole faces during fMRI scan, and performed a post-scan face recognition task using blurred or scrambled faces. The fusiform face area (FFA) showed stronger activation to blurred than to scrambled faces, and equivalent responses to blurred and whole faces. The occipital face area (OFA) showed stronger activation to whole than to blurred faces, which elicited similar responses to scrambled faces. Therefore, the FFA may be more tuned to process configural than componential information, whereas the OFA similarly participates in perception of both. Differences in recognizing own- and other-race blurred faces were correlated with differences in FFA activation to those faces, suggesting that configural processing within the FFA may underlie the other-race effect in face recognition.


Subject(s)
Discrimination, Psychological/physiology , Occipital Lobe/physiology , Pattern Recognition, Visual/physiology , Recognition, Psychology/physiology , Temporal Lobe/physiology , Adult , Face , Female , Humans , Magnetic Resonance Imaging/methods , Male , Racial Groups/psychology , Young Adult
13.
J Vis ; 12(6): 15, 2012 Jun 12.
Article in English | MEDLINE | ID: mdl-22693333

ABSTRACT

Flanked objects are difficult to identify using peripheral vision due to visual crowding, which limits conscious access to target identity. Nonetheless, certain types of visual information have been shown to survive crowding. Such resilience to crowding provides valuable information about the underlying neural mechanism of crowding. Here we ask whether illusory contour formation survives crowding of the inducers. We manipulated the presence of illusory contours through the (mis)alignment of the four inducers of a Kanizsa square. In the inducer-aligned condition, the observers judged the perceived shape (thin vs. fat) of the illusory Kanizsa square, manipulated by small rotations of the inducers. In the inducer-misaligned condition, three of the four inducers (all except the upper-left) were rotated 90°. The observers judged the orientation of the upper-left inducer. Crowding of the inducers worsened observers' performance significantly only in the inducer-misaligned condition. Our findings suggest that information for illusory contour formation survives crowding of the inducers. Crowding happens at a stage where the low-level featural information is integrated for inducer orientation discrimination, but not at a stage where the same information is used for illusory contour formation.


Subject(s)
Crowding , Form Perception/physiology , Illusions/physiology , Visual Fields/physiology , Adult , Contrast Sensitivity/physiology , Discrimination, Psychological/physiology , Humans , Models, Neurological , Photic Stimulation/methods , Sensory Thresholds/physiology , Young Adult
14.
Cogn Emot ; 26(2): 209-23, 2012.
Article in English | MEDLINE | ID: mdl-21614702

ABSTRACT

The present study explored the nature of attention control problems associated with ruminative traits. Experiment 1 aimed to establish the validity of a modified mental counting task that assesses individuals' ability to switch attention between internal mental representations. Reaction time and brain activity (event related potential; ERP) measures were examined, and results showed that the task was sensitive to internal attention switching effects. Experiment 2 assessed how the relationship between ruminative tendencies and switching performance differs when participants attend to neutral versus affective materials under different mood states. Although reaction-time analysis suggested that both mood condition and stimulus affectivity were not significant in altering this association, ERP analysis suggested otherwise. A significant task type×trait rumination × mood condition effect was found for switch-related ERP responses, whereby high ruminators were found to deploy more neuronal resources when switching affective materials in sad mood state.


Subject(s)
Attention/physiology , Psychomotor Performance/physiology , Thinking/physiology , Adolescent , Adult , Affect/physiology , Electroencephalography/methods , Electroencephalography/psychology , Electrooculography/methods , Electrooculography/psychology , Evoked Potentials/physiology , Female , Humans , Male , Personality Inventory/statistics & numerical data , Photic Stimulation/methods , Reaction Time/physiology , Visual Perception/physiology
15.
PLoS One ; 6(12): e28814, 2011.
Article in English | MEDLINE | ID: mdl-22194919

ABSTRACT

BACKGROUND: Human object recognition degrades sharply as the target object moves from central vision into peripheral vision. In particular, one's ability to recognize a peripheral target is severely impaired by the presence of flanking objects, a phenomenon known as visual crowding. Recent studies on how visual awareness of flanker existence influences crowding had shown mixed results. More importantly, it is not known whether conscious awareness of the existence of both the target and flankers are necessary for crowding to occur. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that crowding persists even when people are completely unaware of the flankers, which are rendered invisible through the continuous flash suppression technique. Contrast threshold for identifying the orientation of a grating pattern was elevated in the flanked condition, even when the subjects reported that they were unaware of the perceptually suppressed flankers. Moreover, we find that orientation-specific adaptation is attenuated by flankers even when both the target and flankers are invisible. CONCLUSIONS: These findings complement the suggested correlation between crowding and visual awareness. What's more, our results demonstrate that conscious awareness and attention are not prerequisite for crowding.


Subject(s)
Space Perception/physiology , Visual Perception/physiology , Adaptation, Ocular/physiology , Discrimination, Psychological , Humans , Orientation/physiology , Young Adult
16.
Invest Ophthalmol Vis Sci ; 51(12): 6826-34, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20631240

ABSTRACT

PURPOSE: Activity in regions of the visual cortex corresponding to central scotomas in subjects with macular degeneration (MD) is considered evidence for functional reorganization in the brain. Three unresolved issues related to cortical activity in subjects with MD were addressed: Is the cortical response to stimuli presented to the preferred retinal locus (PRL) different from other retinal loci at the same eccentricity? What effect does the role of age of onset and etiology of MD have on cortical responses? How do functional responses in an MD subject's visual cortex vary for task and stimulus conditions? METHODS: Eight MD subjects-four with age-related onset (AMD) and four with juvenile onset (JMD)-and two age-matched normal vision controls, participated in three testing conditions while undergoing functional magnetic resonance imaging (fMRI). First, subjects viewed a small stimulus presented at the PRL compared with a non-PRL control location to investigate the role of the PRL. Second, they viewed a full-field flickering checkerboard compared with a small stimulus in the original fovea to investigate brain activation with passive viewing. Third, they performed a one-back task with scene images to investigate brain activation with active viewing. RESULTS: A small stimulus at the PRL generated more extensive cortical activation than at a non-PRL location, but neither yielded activation in the foveal cortical projection. Both passive and active viewing of full-field stimuli left a silent zone at the posterior pole of the occipital cortex, implying a lack of complete cortical reorganization. The silent zone was smaller in the task requiring active viewing compared with the task requiring passive viewing, especially in JMD subjects. CONCLUSIONS: The PRL for MD subjects has more extensive cortical representation than a retinal region with matched eccentricity. There is evidence for incomplete functional reorganization of early visual cortex in both JMD and AMD. Functional reorganization is more prominent in JMD. Feedback signals, possibly associated with attention, play an important role in the reorganization.


Subject(s)
Macular Degeneration/physiopathology , Retina/physiopathology , Visual Cortex/physiopathology , Visual Perception/physiology , Adult , Aged , Aged, 80 and over , Contrast Sensitivity , Humans , Magnetic Resonance Imaging , Middle Aged , Neuronal Plasticity/physiology , Scotoma/physiopathology , Stargardt Disease , Visual Acuity , Visual Field Tests
17.
Vision Res ; 50(9): 860-9, 2010 Apr 21.
Article in English | MEDLINE | ID: mdl-20156473

ABSTRACT

Enhancing reading ability in peripheral vision is important for the rehabilitation of people with central-visual-field loss from age-related macular degeneration (AMD). Previous research has shown that perceptual learning, based on a trigram letter-recognition task, improved peripheral reading speed among normally-sighted young adults (Chung, Legge, & Cheung, 2004). Here we ask whether the same happens in older adults in an age range more typical of the onset of AMD. Eighteen normally-sighted subjects, aged 55-76years, were randomly assigned to training or control groups. Visual-span profiles (plots of letter-recognition accuracy as a function of horizontal letter position) and RSVP reading speeds were measured at 10 degrees above and below fixation during pre- and post-tests for all subjects. Training consisted of repeated measurements of visual-span profiles at 10 degrees below fixation, in four daily sessions. The control subjects did not receive any training. Perceptual learning enlarged the visual spans in both trained (lower) and untrained (upper) visual fields. Reading speed improved in the trained field by 60% when the trained print size was used. The training benefits for these older subjects were weaker than the training benefits for young adults found by Chung et al. Despite the weaker training benefits, perceptual learning remains a potential option for low-vision reading rehabilitation among older adults.


Subject(s)
Learning , Reading , Visual Fields/physiology , Visual Perception/physiology , Aged , Aging/physiology , Female , Humans , Male , Middle Aged , Task Performance and Analysis , Time Factors
18.
Curr Biol ; 19(7): 596-601, 2009 Apr 14.
Article in English | MEDLINE | ID: mdl-19361999

ABSTRACT

Although previous studies have shown that Braille reading and other tactile discrimination tasks activate the visual cortex of blind and sighted people, it is not known whether this kind of crossmodal reorganization is influenced by retinotopic organization. We have addressed this question by studying "S," a visually impaired adult with the rare ability to read print visually and Braille by touch. S had normal visual development until 6 years of age, and thereafter severe acuity reduction due to corneal opacification, but no evidence of visual-field loss. Functional magnetic resonance imaging revealed that, in S's early visual areas, tactile information processing activated what would be the foveal representation for normally sighted individuals, and visual information processing activated what would be the peripheral representation. Control experiments showed that this activation pattern was not due to visual imagery. S's high-level visual areas, which correspond to shape- and object-selective areas in normally sighted individuals, were activated by both visual and tactile stimuli. The retinotopically specific reorganization in early visual areas suggests an efficient redistribution of neural resources in the visual cortex.


Subject(s)
Brain Mapping , Pattern Recognition, Physiological/physiology , Touch Perception/physiology , Touch/physiology , Visual Cortex , Adult , Child , Fovea Centralis/physiology , Humans , Magnetic Resonance Imaging , Male , Photic Stimulation , Visual Cortex/anatomy & histology , Visual Cortex/physiology
19.
Invest Ophthalmol Vis Sci ; 49(2): 828-35, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18235034

ABSTRACT

PURPOSE: It is often difficult to estimate parameters from individual clinical data because of noisy or incomplete measurements. Nonlinear mixed-effects (NLME) modeling provides a statistical framework for analyzing population parameters and the associated variations, even when individual data sets are incomplete. The authors demonstrate the application of NLME by analyzing data from the MNREAD, a continuous-text reading-acuity chart. METHODS: The authors analyzed MNREAD data (measurements of reading speed vs. print size) for two groups: 42 adult observers with normal vision and 14 patients with age-related macular degeneration (AMD). Truncated sets of MNREAD data were generated from the individual observers with normal vision. The MNREAD data were fitted with a two-limb function and an exponential-decay function using an individual curve-fitting approach and an NLME modeling approach. RESULTS: The exponential-decay function provided slightly better fits than the two-limb function. When the parameter estimates from the truncated data sets were used to predict the missing data, NLME modeling gave better predictions than individual fitting. NLME modeling gave reasonable parameter estimates for AMD patients even when individual fitting returned unrealistic estimates. CONCLUSIONS: These analyses showed that (1) an exponential-decay function fits MNREAD data very well, (2) NLME modeling provides a statistical framework for analyzing MNREAD data, and (3) NLME analysis provides a way of estimating MNREAD parameters even for incomplete data sets. The present results demonstrate the potential value of NLME modeling for clinical vision data.


Subject(s)
Nonlinear Dynamics , Reading , Vision Tests/methods , Visual Acuity/physiology , Adult , Aged , Female , Humans , Language , Male , Middle Aged
20.
Vision Res ; 48(4): 577-88, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18191983

ABSTRACT

PURPOSE: Visual-span profiles are plots of letter-recognition accuracy as a function of letter position left and right of the point of fixation. Legge, Mansfield, and Chung [Legge, G. E., Mansfield, J. S., & Chung, S. T. L. (2001). Psychophysics of reading-XX. Linking letter recognition to reading speed in central and peripheral vision. Vision Research, 41(6), 725-743] proposed that reduced size of the visual span is a spatial factor limiting reading speed in patients with age-related macular degeneration (AMD). We have recently shown that a temporal property of letter recognition--the exposure time required for a high level of accuracy--is also a factor limiting reading speed in AMD [Cheong, A. M. Y., Legge, G. E., Lawrence, M. G., Cheung, S. H., & Ruff, M. (2007). Relationship between slow visual processing and reading speed in people with macular degeneration. Vision Research, 47, 2943-2965]. We measured the visual-span profiles of AMD subjects and assessed the relationship of the spatial and temporal properties of these profiles to reading speed. METHODS: Thirteen AMD subjects and 11 age-matched normals were tested. Visual-span profiles were measured by using the trigram letter-recognition method described by Legge et al. (2001). Each individual's temporal threshold for letter recognition (80% accuracy criterion) was used as the exposure time for measuring the visual-span profile. Size of the visual span was computed as the area under the profile in bits of information transmitted. The information transfer rate in bits per second was defined as the visual-span size in bits divided by the exposure time in sec. RESULTS: AMD visual-span sizes were substantially smaller (median of 23.9 bits) than normal visual-span sizes in central vision (median of 40.8 bits, p<.01). For the nine AMD subjects with eccentric fixation, the visual-span sizes (median of 20.6 bits) were also significantly smaller than visual spans of normal controls at 10 degrees below fixation in peripheral vision (median of 29.0 bits, p=.01). Information transfer rate for the AMD subjects (median of 29.5 bits/s) was significantly slower than that for the age-matched normals at both central and peripheral vision (median of 411.7 and 290.5 bits/s respectively, ps<.01). Information transfer rates were more strongly correlated with reading speed than the size of the visual span, and explained 36% of the variance in AMD reading speed. CONCLUSION: Both visual-span size and information transfer rate were significantly impaired in the AMD subjects compared with age-matched normals. Information transfer rate, representing the combined effects of a reduced visual span and slower temporal processing of letters, was a better predictor of reading speed in AMD subjects than was the size of the visual span.


Subject(s)
Macular Degeneration/physiopathology , Pattern Recognition, Visual , Reading , Aged , Aged, 80 and over , Contrast Sensitivity , Fixation, Ocular , Humans , Macular Degeneration/complications , Macular Degeneration/psychology , Photic Stimulation/methods , Psychophysics , Scotoma/physiopathology , Sensory Thresholds , Vision Tests/methods , Vision, Low/etiology , Vision, Low/physiopathology , Vision, Low/psychology , Visual Acuity
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