The colour-vision losses in blue-yellow acquired colour-vision deficiencies
have been likened to... more The colour-vision losses in blue-yellow acquired colour-vision deficiencies
have been likened to the performance of normal subject~ at low luminance
levels and described as a 'mesopization'. The B-Y colour-vision deficiency
seen in diabetic patients ha~ been shown to be enhanced when short-duration
stimuli are used in patients without retinopathy (Scase et al, 1990). To assess
whether mesopization can also explain losses with brief stimuli. hue-discrimination
performance was determined along the cardinal directions of colour
space in subjects with normal colour vision over a range of luminances from
7.0 to 0.025 cd m-2. Stimuli were presented on a colour video-display
system. This technique has the advantage, unlike the Farnsworth-Munsell
I 00-Hue Test on which the mesopization hypothesis was based, of having no
possible bias towards B-Y thresholds compared with red-green thresholds
when screen luminance was reduced. This was true for both long- and short duration
stimuli. Therefore mesopization cannot account for the specific
deficits in B-Y discrimination previously demonstrated by this technique
in diabetic patients. especially those found with short-duration stimuli in
patients without retinopathy. A specific loss in blue-yellow processing is
indicated.
Fears of compassion are feelings of threat towards receiving and giving kindness. This study exam... more Fears of compassion are feelings of threat towards receiving and giving kindness. This study examined the fears towards compassion on physiological responses during compassionate exercises. It has been argued that such fears are a barrier to a relaxation system normally reducing physiological activity but there has been no empirical evidence to support this. Exercises have been developed to increase compassion by activating a physiological soothing system, however if fears to compassion block the effectiveness of compassion then new methods may need to be developed to increase self-compassion.
Colour vision function was assessed in 38 noncomplicated type 1 diabetic patients in whom fluores... more Colour vision function was assessed in 38 noncomplicated type 1 diabetic patients in whom fluorescein angiography was normal, and was compared with that in 36 age-matched, nondiabetic controls. All of the patients were healthy and none were taking medication except insulin. The eye examination, which was normal in every patient, included the Ishihara and City University tests, measurement of Snellen acuity, slit-lamp examination, tonometry, and fundal photography as well as. fluorescein angiography. Colour discrimination ability was measured with the Farnsworth-Munsell 100-hue test. Mean (SE) 100-hue test error score for the diabetic group was 86*8 (8. 1) compared with 28*2 (3.3) for controls, p<<0001. There was no relation between colour vision abnormalities and diabetes duration (r=0, p>005), blood glucose at the time the colour tests were performed (r=0.4, p>005), most recent glycated haemoglobin result (r=0.3, p>005), or the mean of all previous glycated haemoglobin results (r=0, p>005). It is concluded that colourdiscrimination may be abnormal in uncomplicated type 1 diabetic patients before the onset of retinopathy, and that colour discrimination losses in diabetes may not be of vascular aetiology.
Ahatraet-An experimental examination was made of some paradigms designed to isolate the opponentc... more Ahatraet-An experimental examination was made of some paradigms designed to isolate the opponentcolour system at increment threshold. The effectiveness of a uniform white conditioning field spatially coincident with a l.OS-deg uniform test field was amessed by measuring intensity thresholds for simple detection and for colour discrimination. Values were obtained both by a method of adjustment and by a two-interval famed-choice procedure. For sutBciently high lmninances of the conditioning field (3000 td or greater) little or no difference was found between simple-detection and colour-discrimination thresholds over the critical test-flash spectral range 520-620nm. implying that the paradigm produced almost complete isolation of the opponent-colour system at increment threshold. A control experiment in which thresholds were. obtained for a conditioning field larger than the test field gave less satisfactory isolation; near 58Onm the luminance system was found to be at least 0.3 log unit more sensitive than the opponent-colour system. A comparison was also made of the spatially coincident field paradigm with a paradigm in which a modified test stimulus of low temporal and spatial frequency content was presented on a large conditioning field. Test spectral sensitivity curves for simple detection obtained by a method of adjustment showed little diflerence in etfectiveness in opponent-colour isolation. Gpponentcolour system Luminance system Spectral sensitivity Spectral sharpening INTBODUCTION *Some of the data reported here were contained in a paper presented to The Colour Group (Great Britain), January 1985, and in a Communication ptemnted to the Physiological Society (Foster, Scase and Snelgar, 1986).
ABSTRACT In this paper, we describe a project concerned with embedding Teaching and Learning Tech... more ABSTRACT In this paper, we describe a project concerned with embedding Teaching and Learning Technology Programme (TLTP) and other resource based learning materials (RBL) as major components in the teaching of undergraduate psychology courses. Our use of the term “RBL” is quite broad but refers mainly to computer aided learning (CAL) materials which have been downloaded from the Internet or obtained on floppy disc or CD-ROM. The project is one of a series of projects being carried out at De Montfort University (DMU) as part of an institution-wide initiative concerned with facilitating and encouraging the increased use of RBL. There is a modest centrally-administered budget for the purchase of materials and to buy out staff time. There is additional input from educational technologists, based in the University&#39;s Centre for Educational Technology and Development (CETD). Within the Department of Human Communication, the project is serving as a pilot study to inform policy and practice. The project is on a relatively large scale, affecting 120 students studying psychology and psychology-related modules, commencing in September, 1997. As well as serving as a general set of resources that students may access as part of private study, some of the resources are fully embedded in the teaching programmes as part of timetabled sessions. For these sessions, worksheets and other text-based materials are provided, as necessary, to ensure that learning activities are properly goal-directed and supported by formative and summative assessment. The use and effectiveness of the materials is being assessed as part of an ongoing evaluation programme, involving both staff and students. Here, we report on outcomes and progress to date.
Studies in Health Technology and Informatics, 2017
The older population of Europe is increasing and there has been a corresponding increase in long ... more The older population of Europe is increasing and there has been a corresponding increase in long term care costs. This project sought to promote active ageing by delivering tasks via a tablet computer to participants aged 65-80 with mild cognitive impairment. An age-appropriate gamified environment was developed and adherence to this solution was assessed through an intervention. The gamified environment was developed through focus groups. Mixed methods were used in the intervention with the time spent engaging with applications recorded supplemented by participant interviews to gauge adherence. There were two groups of participants: one living in a retirement village and the other living separately across a city. The retirement village participants engaged in more than three times the number of game sessions compared to the other group possibly because of different social arrangements between the groups. A gamified environment can help older people engage in computer-based applicat...
Foveal pathway visual function was assessed in 11 patients having tumours extending into the supr... more Foveal pathway visual function was assessed in 11 patients having tumours extending into the suprasellar region but without evidence of visual impairment as assessed by visual acuity and Bjerrum screen campimetry. Psychophysical and routine visual evoked potential (VEP) measure-ments were obtained from the eye ipsilateral to the maximal suprasellar extension. The sensitivity of luminance and chromatic pathways was assessed psychophysically by measuring increment thresholds for white and red flashes of light presented on a white adapting field. Temporal sensitivity was assessed psychophysically by measuring threshold modulation sensitivity for sinusoidally modulating stimuli (de Lange attenuation characteristic). The patient group showed approximately equal significant psychophysical losses in chromatic, luminance and temporal sensitivities relative to normal controls. Midline VEP P100 latencies of the patient group did not significantly differ from those of the normal control group....
This study aimed to identify if compassion benefits paranoia and, if so what type of compassion. ... more This study aimed to identify if compassion benefits paranoia and, if so what type of compassion. Following a series of different compassionate exercises in 104 participants it was found that mindfulness approaches were the most significant in reducing paranoia suggesting a new approach for psychological problems characterised by paranoia. Introduction Paranoia is a characteristic common to many psychological problems such as depression, schizophrenia and anxiety and refers to irrational and unrealistic beliefs of grandeur, threat, persecution and suspicion. Such beliefs can cause significant distress to the thinker and may pervade interpersonal relationships and daily functioning. A vulnerability to paranoid thoughts has roots in the non-clinical general population. Increased vulnerability to paranoid beliefs can produce paranoid ideation. Social media platforms expand available stimuli to perceive threats for example from ideals of body weight, education and money. The opposite to ...
1De Montfort University, Leicester, UK, 2Imperial College London, UK. Abstract Pre-navigational t... more 1De Montfort University, Leicester, UK, 2Imperial College London, UK. Abstract Pre-navigational tools can assist visually impaired people when navigating unfamiliar environments. We assessed the effectiveness of an interactive audio-tactile-map (ATM) in blind and visually impaired people. We found that participants exposed to an ATM recalled the map significantly better than those given a conventional tactile map accompanied by text description.
The effects of reduced stimulus duration on colour vision were assessed in two pathologies differ... more The effects of reduced stimulus duration on colour vision were assessed in two pathologies differentially affecting the optic nerve and retina. Hue-discrimination thresholds were measured for long and short-duration (500 and 2 ms) stimuli presented on a computer-controlled colour monitor in 10 patients with previous optic neuritis, in 17 diabetic patients, 8 with and 9 without retinopathy, and in 10 normal controls. All patient groups had normal Farnsworth-Munsell 100-Hue scores. Thresholds were obtained by a hybrid-adaptive procedure requiring hue discrimination about a reference white. As flash duration was reduced, normal subjects showed greater threshold elevations along the red-green axis than along the tritanopic axis. For patients with previous optic neuritis, performance was similar to, but uniformly worse than, that of controls. In contrast, for diabetic patients without retinopathy, reduced flash duration had the effect of increasing thresholds more along the tritanopic ax...
Studies in health technology and informatics, 2018
BACKGROUND In Europe the number of elderly people is increasing. This population growth has resul... more BACKGROUND In Europe the number of elderly people is increasing. This population growth has resulted in higher healthcare costs. The purpose of this project was to try to promote active ageing in people aged 65-80 with mild cognitive impairment through cognitive games delivered via a tablet computer. OBJECTIVES Age-appropriate cognitive games were developed targeting different aspects of cognition and then experiences of elderly people using these games were evaluated. METHODS The design of games was developed through iterative user-centered design focus groups with elderly people as participants. The experiences of participants playing the games over a 47 day period were explored through semi-structured interviews. RESULTS Four games were developed that addressed a range of cognitive functions such as perception, attention, memory, language, comprehension and executive function. The participants were able to play these games without external intervention over an extended period and...
Overview and aims: This project aimed to promote active aging by delivering tasks via a tablet co... more Overview and aims: This project aimed to promote active aging by delivering tasks via a tablet computer to participants aged 65-80 with mild cognitive impairment. The aims were to develop an age-appropriate gamified environment and to assess application adherence through an intervention. Methods: The gamified environment was developed through a series of three iterative usercentered focus groups. Adherence was assessed by the time spent engaging with applications over 47 days supplemented with participant interviews. There were two groups of participants: one of 11 people living in a retirement village (1 male; mean age=75.4, SD=5.14; mean MoCA=26.0, SD=2.28) and the other of 13 people living separately across a city (1 male; mean age=74.9, SD=3.68; mean MoCA=24.4, SD=1.19). Results: There was a significant difference in the mean number of sessions for retirement village participants (mean=29.1, SD=14.8) and those living separately (mean=8.8, SD=7.5), adjusted t(14.3)=4.1, p=0.001 w...
Feature selective validation (FSV) is an international standard for comparing vi- sually complex ... more Feature selective validation (FSV) is an international standard for comparing vi- sually complex 1D data. Initial veriflcation of FSV was performed by presenting a visual rating chart accompanying comparative data. Eye-scanning data was analysed from observers as they compared graphically presented data. However, little is understood about how observers inter- pret displays of multidimensional datasets. We have been applying psychological principles of judgment and decision making to investigate the processes involved in this task. The goal has been to establish the main factors that in∞uence observers when they make decisions when view- ing displays. The interpretation of complex scenes by human observers to recognise or detect particular features is limited by the structure and performance of the visual system. Therefore to devise displays for observers to detect features from n-dimensional data sets one needs to appre- ciate the functional limitations of our perceptual system. Fi...
The colour-vision losses in blue-yellow acquired colour-vision deficiencies
have been likened to... more The colour-vision losses in blue-yellow acquired colour-vision deficiencies
have been likened to the performance of normal subject~ at low luminance
levels and described as a 'mesopization'. The B-Y colour-vision deficiency
seen in diabetic patients ha~ been shown to be enhanced when short-duration
stimuli are used in patients without retinopathy (Scase et al, 1990). To assess
whether mesopization can also explain losses with brief stimuli. hue-discrimination
performance was determined along the cardinal directions of colour
space in subjects with normal colour vision over a range of luminances from
7.0 to 0.025 cd m-2. Stimuli were presented on a colour video-display
system. This technique has the advantage, unlike the Farnsworth-Munsell
I 00-Hue Test on which the mesopization hypothesis was based, of having no
possible bias towards B-Y thresholds compared with red-green thresholds
when screen luminance was reduced. This was true for both long- and short duration
stimuli. Therefore mesopization cannot account for the specific
deficits in B-Y discrimination previously demonstrated by this technique
in diabetic patients. especially those found with short-duration stimuli in
patients without retinopathy. A specific loss in blue-yellow processing is
indicated.
Fears of compassion are feelings of threat towards receiving and giving kindness. This study exam... more Fears of compassion are feelings of threat towards receiving and giving kindness. This study examined the fears towards compassion on physiological responses during compassionate exercises. It has been argued that such fears are a barrier to a relaxation system normally reducing physiological activity but there has been no empirical evidence to support this. Exercises have been developed to increase compassion by activating a physiological soothing system, however if fears to compassion block the effectiveness of compassion then new methods may need to be developed to increase self-compassion.
Colour vision function was assessed in 38 noncomplicated type 1 diabetic patients in whom fluores... more Colour vision function was assessed in 38 noncomplicated type 1 diabetic patients in whom fluorescein angiography was normal, and was compared with that in 36 age-matched, nondiabetic controls. All of the patients were healthy and none were taking medication except insulin. The eye examination, which was normal in every patient, included the Ishihara and City University tests, measurement of Snellen acuity, slit-lamp examination, tonometry, and fundal photography as well as. fluorescein angiography. Colour discrimination ability was measured with the Farnsworth-Munsell 100-hue test. Mean (SE) 100-hue test error score for the diabetic group was 86*8 (8. 1) compared with 28*2 (3.3) for controls, p<<0001. There was no relation between colour vision abnormalities and diabetes duration (r=0, p>005), blood glucose at the time the colour tests were performed (r=0.4, p>005), most recent glycated haemoglobin result (r=0.3, p>005), or the mean of all previous glycated haemoglobin results (r=0, p>005). It is concluded that colourdiscrimination may be abnormal in uncomplicated type 1 diabetic patients before the onset of retinopathy, and that colour discrimination losses in diabetes may not be of vascular aetiology.
Ahatraet-An experimental examination was made of some paradigms designed to isolate the opponentc... more Ahatraet-An experimental examination was made of some paradigms designed to isolate the opponentcolour system at increment threshold. The effectiveness of a uniform white conditioning field spatially coincident with a l.OS-deg uniform test field was amessed by measuring intensity thresholds for simple detection and for colour discrimination. Values were obtained both by a method of adjustment and by a two-interval famed-choice procedure. For sutBciently high lmninances of the conditioning field (3000 td or greater) little or no difference was found between simple-detection and colour-discrimination thresholds over the critical test-flash spectral range 520-620nm. implying that the paradigm produced almost complete isolation of the opponent-colour system at increment threshold. A control experiment in which thresholds were. obtained for a conditioning field larger than the test field gave less satisfactory isolation; near 58Onm the luminance system was found to be at least 0.3 log unit more sensitive than the opponent-colour system. A comparison was also made of the spatially coincident field paradigm with a paradigm in which a modified test stimulus of low temporal and spatial frequency content was presented on a large conditioning field. Test spectral sensitivity curves for simple detection obtained by a method of adjustment showed little diflerence in etfectiveness in opponent-colour isolation. Gpponentcolour system Luminance system Spectral sensitivity Spectral sharpening INTBODUCTION *Some of the data reported here were contained in a paper presented to The Colour Group (Great Britain), January 1985, and in a Communication ptemnted to the Physiological Society (Foster, Scase and Snelgar, 1986).
ABSTRACT In this paper, we describe a project concerned with embedding Teaching and Learning Tech... more ABSTRACT In this paper, we describe a project concerned with embedding Teaching and Learning Technology Programme (TLTP) and other resource based learning materials (RBL) as major components in the teaching of undergraduate psychology courses. Our use of the term “RBL” is quite broad but refers mainly to computer aided learning (CAL) materials which have been downloaded from the Internet or obtained on floppy disc or CD-ROM. The project is one of a series of projects being carried out at De Montfort University (DMU) as part of an institution-wide initiative concerned with facilitating and encouraging the increased use of RBL. There is a modest centrally-administered budget for the purchase of materials and to buy out staff time. There is additional input from educational technologists, based in the University&#39;s Centre for Educational Technology and Development (CETD). Within the Department of Human Communication, the project is serving as a pilot study to inform policy and practice. The project is on a relatively large scale, affecting 120 students studying psychology and psychology-related modules, commencing in September, 1997. As well as serving as a general set of resources that students may access as part of private study, some of the resources are fully embedded in the teaching programmes as part of timetabled sessions. For these sessions, worksheets and other text-based materials are provided, as necessary, to ensure that learning activities are properly goal-directed and supported by formative and summative assessment. The use and effectiveness of the materials is being assessed as part of an ongoing evaluation programme, involving both staff and students. Here, we report on outcomes and progress to date.
Studies in Health Technology and Informatics, 2017
The older population of Europe is increasing and there has been a corresponding increase in long ... more The older population of Europe is increasing and there has been a corresponding increase in long term care costs. This project sought to promote active ageing by delivering tasks via a tablet computer to participants aged 65-80 with mild cognitive impairment. An age-appropriate gamified environment was developed and adherence to this solution was assessed through an intervention. The gamified environment was developed through focus groups. Mixed methods were used in the intervention with the time spent engaging with applications recorded supplemented by participant interviews to gauge adherence. There were two groups of participants: one living in a retirement village and the other living separately across a city. The retirement village participants engaged in more than three times the number of game sessions compared to the other group possibly because of different social arrangements between the groups. A gamified environment can help older people engage in computer-based applicat...
Foveal pathway visual function was assessed in 11 patients having tumours extending into the supr... more Foveal pathway visual function was assessed in 11 patients having tumours extending into the suprasellar region but without evidence of visual impairment as assessed by visual acuity and Bjerrum screen campimetry. Psychophysical and routine visual evoked potential (VEP) measure-ments were obtained from the eye ipsilateral to the maximal suprasellar extension. The sensitivity of luminance and chromatic pathways was assessed psychophysically by measuring increment thresholds for white and red flashes of light presented on a white adapting field. Temporal sensitivity was assessed psychophysically by measuring threshold modulation sensitivity for sinusoidally modulating stimuli (de Lange attenuation characteristic). The patient group showed approximately equal significant psychophysical losses in chromatic, luminance and temporal sensitivities relative to normal controls. Midline VEP P100 latencies of the patient group did not significantly differ from those of the normal control group....
This study aimed to identify if compassion benefits paranoia and, if so what type of compassion. ... more This study aimed to identify if compassion benefits paranoia and, if so what type of compassion. Following a series of different compassionate exercises in 104 participants it was found that mindfulness approaches were the most significant in reducing paranoia suggesting a new approach for psychological problems characterised by paranoia. Introduction Paranoia is a characteristic common to many psychological problems such as depression, schizophrenia and anxiety and refers to irrational and unrealistic beliefs of grandeur, threat, persecution and suspicion. Such beliefs can cause significant distress to the thinker and may pervade interpersonal relationships and daily functioning. A vulnerability to paranoid thoughts has roots in the non-clinical general population. Increased vulnerability to paranoid beliefs can produce paranoid ideation. Social media platforms expand available stimuli to perceive threats for example from ideals of body weight, education and money. The opposite to ...
1De Montfort University, Leicester, UK, 2Imperial College London, UK. Abstract Pre-navigational t... more 1De Montfort University, Leicester, UK, 2Imperial College London, UK. Abstract Pre-navigational tools can assist visually impaired people when navigating unfamiliar environments. We assessed the effectiveness of an interactive audio-tactile-map (ATM) in blind and visually impaired people. We found that participants exposed to an ATM recalled the map significantly better than those given a conventional tactile map accompanied by text description.
The effects of reduced stimulus duration on colour vision were assessed in two pathologies differ... more The effects of reduced stimulus duration on colour vision were assessed in two pathologies differentially affecting the optic nerve and retina. Hue-discrimination thresholds were measured for long and short-duration (500 and 2 ms) stimuli presented on a computer-controlled colour monitor in 10 patients with previous optic neuritis, in 17 diabetic patients, 8 with and 9 without retinopathy, and in 10 normal controls. All patient groups had normal Farnsworth-Munsell 100-Hue scores. Thresholds were obtained by a hybrid-adaptive procedure requiring hue discrimination about a reference white. As flash duration was reduced, normal subjects showed greater threshold elevations along the red-green axis than along the tritanopic axis. For patients with previous optic neuritis, performance was similar to, but uniformly worse than, that of controls. In contrast, for diabetic patients without retinopathy, reduced flash duration had the effect of increasing thresholds more along the tritanopic ax...
Studies in health technology and informatics, 2018
BACKGROUND In Europe the number of elderly people is increasing. This population growth has resul... more BACKGROUND In Europe the number of elderly people is increasing. This population growth has resulted in higher healthcare costs. The purpose of this project was to try to promote active ageing in people aged 65-80 with mild cognitive impairment through cognitive games delivered via a tablet computer. OBJECTIVES Age-appropriate cognitive games were developed targeting different aspects of cognition and then experiences of elderly people using these games were evaluated. METHODS The design of games was developed through iterative user-centered design focus groups with elderly people as participants. The experiences of participants playing the games over a 47 day period were explored through semi-structured interviews. RESULTS Four games were developed that addressed a range of cognitive functions such as perception, attention, memory, language, comprehension and executive function. The participants were able to play these games without external intervention over an extended period and...
Overview and aims: This project aimed to promote active aging by delivering tasks via a tablet co... more Overview and aims: This project aimed to promote active aging by delivering tasks via a tablet computer to participants aged 65-80 with mild cognitive impairment. The aims were to develop an age-appropriate gamified environment and to assess application adherence through an intervention. Methods: The gamified environment was developed through a series of three iterative usercentered focus groups. Adherence was assessed by the time spent engaging with applications over 47 days supplemented with participant interviews. There were two groups of participants: one of 11 people living in a retirement village (1 male; mean age=75.4, SD=5.14; mean MoCA=26.0, SD=2.28) and the other of 13 people living separately across a city (1 male; mean age=74.9, SD=3.68; mean MoCA=24.4, SD=1.19). Results: There was a significant difference in the mean number of sessions for retirement village participants (mean=29.1, SD=14.8) and those living separately (mean=8.8, SD=7.5), adjusted t(14.3)=4.1, p=0.001 w...
Feature selective validation (FSV) is an international standard for comparing vi- sually complex ... more Feature selective validation (FSV) is an international standard for comparing vi- sually complex 1D data. Initial veriflcation of FSV was performed by presenting a visual rating chart accompanying comparative data. Eye-scanning data was analysed from observers as they compared graphically presented data. However, little is understood about how observers inter- pret displays of multidimensional datasets. We have been applying psychological principles of judgment and decision making to investigate the processes involved in this task. The goal has been to establish the main factors that in∞uence observers when they make decisions when view- ing displays. The interpretation of complex scenes by human observers to recognise or detect particular features is limited by the structure and performance of the visual system. Therefore to devise displays for observers to detect features from n-dimensional data sets one needs to appre- ciate the functional limitations of our perceptual system. Fi...
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Papers by Mark Scase
have been likened to the performance of normal subject~ at low luminance
levels and described as a 'mesopization'. The B-Y colour-vision deficiency
seen in diabetic patients ha~ been shown to be enhanced when short-duration
stimuli are used in patients without retinopathy (Scase et al, 1990). To assess
whether mesopization can also explain losses with brief stimuli. hue-discrimination
performance was determined along the cardinal directions of colour
space in subjects with normal colour vision over a range of luminances from
7.0 to 0.025 cd m-2. Stimuli were presented on a colour video-display
system. This technique has the advantage, unlike the Farnsworth-Munsell
I 00-Hue Test on which the mesopization hypothesis was based, of having no
possible bias towards B-Y thresholds compared with red-green thresholds
when screen luminance was reduced. This was true for both long- and short duration
stimuli. Therefore mesopization cannot account for the specific
deficits in B-Y discrimination previously demonstrated by this technique
in diabetic patients. especially those found with short-duration stimuli in
patients without retinopathy. A specific loss in blue-yellow processing is
indicated.
have been likened to the performance of normal subject~ at low luminance
levels and described as a 'mesopization'. The B-Y colour-vision deficiency
seen in diabetic patients ha~ been shown to be enhanced when short-duration
stimuli are used in patients without retinopathy (Scase et al, 1990). To assess
whether mesopization can also explain losses with brief stimuli. hue-discrimination
performance was determined along the cardinal directions of colour
space in subjects with normal colour vision over a range of luminances from
7.0 to 0.025 cd m-2. Stimuli were presented on a colour video-display
system. This technique has the advantage, unlike the Farnsworth-Munsell
I 00-Hue Test on which the mesopization hypothesis was based, of having no
possible bias towards B-Y thresholds compared with red-green thresholds
when screen luminance was reduced. This was true for both long- and short duration
stimuli. Therefore mesopization cannot account for the specific
deficits in B-Y discrimination previously demonstrated by this technique
in diabetic patients. especially those found with short-duration stimuli in
patients without retinopathy. A specific loss in blue-yellow processing is
indicated.