Laws Flashcards
- As the intensity of illumination increases in geometric progression, the strength of sensation increases arithmetically
- the sensation varies as the logarithm of the intensity of the stimulus
Fechner’s law or Psycho-physical law
- The nature of perception is defined by the pathway over which the sensory information is carried.
- origin of sensation is not important
- difference in perception of seeing, hearing and touch are not caused by differences in the stimuli themselves but by the different nervous structures that these stimuli excite
Muller’s law
Innervation to the extraocular muscles is equal to both eye. Thus, all movements of the 2 eyes are equal and symmetrical
Herring’s law of equal innervation
states that the eye orientations can be reached by starting from one specific “primary” reference orientation and then rotating about an axis that lies within the plane orthogonal to the primary orientations gaze direction.
States that the character and amount of the torsion produced when the globe has moved into a tertiary position are the same as that which would have occurred if the eyes had been rotated around a final axis perpendicular to both the first and second direction of the line of sight.
Listing’s Law
States that for any determinate position of the line of fixation with respect to the head, there is a corresponding definite and invariable angle of torsion.
States that for any one gaze direction, the eye always assumes the same unique orientation in 3 dimensions
the orientation of the eye when looking up and right is the same when the eye reached this position by first rotating right and then up or first up and then right
Donder’s law
States that if a continuous sensation results from intermittent stimulation, the brightness of the sensation is the same as if the light received during the various periods of stimulation had been uniformly distributed over the whole time
Talbot-Plateau Law
States that if the stimulated foveal area is decreased, the intensity of the light must be increased and vice versa, that is, the product of the absolute threshold of luminance and the image area is constant
When a light source of a given size and intensity is just capable of producing visual sensation, reduction of either size or intensity will make it invisible
Ricco’s Law
States that the smallest increase or decrease in the strength of the stimulus that can cause a just noticeable increase or decrease in the sensation is a constant fraction of the original stimulus
Weber’s law
it states that neural activity is always maximal, that is, a stimulus is too feeble to cause a response or it elicits a maximum response
All or None Phenomenon law
states that the product of the intensity of the light stimulus and the duration of exposure is constant
Bunsen-Roscoe Law
states that the critical fusion frequency is directly proportional to the logarithm of the intensity of light
Ferry-Potter law
states that an impression made on nay part of the retina is projected outward into the visual field following the line of direction
Law of Projection
