Spatial Contrast Sensitivity of Birds

Contrast sensitivity (CS) is the ability of the observer to discriminate between adjacent stimuli on the basis of their differences in relative luminosity (contrast) rather than their absolute luminances. Prior to this study, birds had been thought to have low contrast detection thresholds relative to mammals and fishes. This was a surprising phenomenon because birds had been traditionally attributed with superior vision…

Contents

CHAPTER 1: Introduction
Contrast Sensitivity
Neural Determinants of the CSF
Optical Determinants of the CSF
Models to Predict the Maximum Height of a CSF
Effects of Stimulus Parameters on the CSF
Number of Cycles
Target Luminance and Retinal Illuminance
Retinal Illuminance Affects Contrast Gain
Luminance Affects Receptive Fields
Stimulus Area
CHAPTER 2: Comparative Literature on Contrast Sensitivity
Overview
Avian CSF
Half-Height Bandwidth
Location of the CSF on the SF-Axis and Physiology
Low Contrast Sensitivity
Research Objective
CHAPTER 3: Behavioral Method of Collecting the CSF
CHAPTER 4: Electrophysiological Method of Collecting the CSF—The Pattern
Electroretinogram
Overview
Temporal Modulation
Neuronal Source of PERG Signal
Interpretations of the PERG Method
Differences between PERG- and behaviorally- generated CSFs
Similarities between PERG- and behaviorally- generated CSFs
CHAPTER 5: Objectives and Procedures
Objectives
Experimental Questions
Methods
Procedure
Subjects
Pharmacological Treatments
PERG Procedure
Stimuli
PERG Analysis
CHAPTER 6: Results
Pigeons
Kestrels
Woodpecker
Quail
Starlings
Owls
CHAPTER 7: Discussion
Avian CSFs
Comparison to the Literature
Pigeons
American Kestrel
Woodpecker
Quail
Starlings
Barn Owls
Ethological Considerations
Pigeons
Kestrels
Woodpeckers
Quail
Starlings
Owls
Aves Compared to Mammalia
The Low Peak Contrast Sensitivity of Birds
Appendix
References

Author: Ghim, Mimi M

Source: University of Maryland

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