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At least 973 records · Page 54Linked to original sources
PubMed2003

Loss of cone function in age-related maculopathy.

PURPOSE: To evaluate cone visual function of subjects with age-related maculopathy (ARM). METHODS: Cone thresholds in 16 patients with ARM and 14 age-matched control subjects were compared. All subjects had visual acuity of 6/12 or better in the studied eye. A range of contrast thresholds were measured to evaluate diverse aspects of cone visual function under steady state conditions (spatiotemporal, color and luminance, and photopic sensitivity) or after bleaching (adaptation dynamics). RESULTS: ARM produced a diffuse loss across all cone steady state visual functions in 31% to 44% of subjects. The adaptation time constant of cone recovery was significantly prolonged in most (69%) ARM eyes. A cross-correlational analysis found adaptational kinetics to be independent of other steady state losses, with cone photopigment regeneration being the most affected visual function in ARM (chi(2) = 4.03, P < 0.05). CONCLUSIONS: The results show that cone-adaptational kinetics are affected in ARM more so than are steady state thresholds. Given that cone recovery is easy to examine in a clinical setting, this test may provide a useful index of photopic function in patients with ARM.

Adaptation, Ocular↗
PubMed2003

The role of lenticular senescence in age-related color vision changes.

PURPOSE: It has been reported that greater age-related losses in sensitivity occur for short-wavelength visual stimuli than for medium- and long-wavelength visual stimuli. The purpose of the current experiment was to determine to what extent optical, receptoral, and postreceptoral factors contribute to these age-related changes in color vision. METHODS: One hundred two observers (ages 18-87) completed a minimum motion task to determine isoluminance between red and green and between red and blue. A motion-nulling task was also performed to assess the L-M postreceptoral chromatic mechanism. RESULTS: No significant age-related changes occurred in red-green isoluminance values. Red-blue isoluminance values showed a significant and systematic decrease with age in observers with phakic eyes. Pseudophakic eyes in older subjects performed this task as well as phakic eyes in young subjects. The motion-nulling results demonstrated small age-related losses in the postreceptoral color mechanisms. CONCLUSIONS: The findings of this experiment, particularly those of the red-blue isoluminance task, indicate that the optical factor of lenticular senescence is the main contributor to the age-related changes observed in color vision. A model based on age-related changes in lenticular absorbance shows good fit with the experimental data of observers with phakic eyes, suggesting that optical factors are the main cause of the age-related changes in these color vision tasks.

Adolescent↗
PubMedDate not supplied

COLOUR VISION.

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Color Perception↗
PubMed2006

Memory recall in arousing situations - an emotional von Restorff effect?

BACKGROUND: Previous research has demonstrated a relationship between memory recall and P300 amplitude in list learning tasks, but the variables mediating this P300-recall relationship are not well understood. In the present study, subjects were required to recall items from lists consisting of 12 words, which were presented in front of pictures taken from the IAPS collection. One word per list is made distinct either by font color or by a highly arousing background IAPS picture. This isolation procedure was first used by von Restorff. Brain potentials were recorded during list presentation. RESULTS: Recall performance was enhanced for color but not for emotional isolates. Event-related brain potentials (ERP) showed a more positive P300-component for recalled non-isolated words and color-isolated words, compared to the respective non-remembered words, but not for words isolated by arousing background. CONCLUSION: Our findings indicate that it is crucial to take emotional mediator variables into account, when using the P300 to predict later recall. Highly arousing environments might force the cognitive system to interrupt rehearsal processes in working memory, which might benefit transfer into other, more stable memory systems. The impact of attention-capturing properties of arousing background stimuli is also discussed.

Adult↗
PubMed1975

Step size in the Munsell color-order system by pair comparisons near 5Y 7.5/1 and bisections near 10R 7/8.

Pair comparisons were used to assess the perceptual uniformity of the Munsell value (V) and chroma (C) scales near 5Y 7.5/1 for both small (0.25-0.75) and larger (1-2) increments in V and C. We conclude that in this region perceptual linearity is retained down to steps of 0.25 V and C. Bisection experiments showed that around 10R 7/8 perceptual linearity in Munsell hue (H), V, and C was retained down to step sizes of 0.25 H, 0.10 V, and 0.25 C.

Adult↗