reverse terms Flashcards
1) something moves in the world - image moves across the retina
2) Things not explained by above
Examples:
something moves and we track it - doesn’t move across the retina
We move our eyes or body – movement of the image across the retina but we don’t perceive movement
Real movement
Assume that detector cell (D) responds when it receives simultaneous input from receptors R1 and R2.
By introducing a delay element (t), detector would only respond to a target moving in one direction
directionally selective circuit:
Specialized motion sensitive mechanisms must represent speed & direction
Reichardt detectors - most modern models elaborate on this type of detector
Retinal Image Motion
The impossibility of determining the actual direction of motion of a stimulus by the response of a single neutron that sees the stills only through a small window and sees inly the component of motion in the bourbons preferred direction.
Solution: Responses of a number of V1 neurons are pooled
This may occur in the medial temporal (MT) cortex, which is located in the where/action stream
Aperture Problem
depends on three signals
-Motor signal (MS) - signal sent to eyes to move eye muscles
-??? - copy of the motor signal
-Image movement signal (IMS); movement of image stimulating receptors across the retina
Movement is perceived when comparator receives input from either ??? or image movement signal
Movement is not perceived when comparator receives input from both ??? and image movement signals
Corollary Discharge Theory
A case in which we see motion when there is none present
Motion aftereffects
occurs when 2 or more lights are flashed in sequence
Depending on the interstimulus interval and the spatial arrangement of the lights, different forms of illusory movement are seen
Apparent Motion
apparent motion tends to occur on the shortest path between two stimuli
Shortest-path constraint
is the incorrect attribution of movement e.g. sitting next to train that moves, moon in clouds, etc.
Occurs typically when larger object moves relative to a smaller one (frame of reference)
Induced movement:
When the shadow of a rotating 3D object is cast on a screen, it looks three-dimensional, even though the shadow is flat.
The kinetic depth effect
structure created by surfaces, textures, and contours, which change as the observer moves through the environment
optic array
Representations provided by perceptual system
Take action capabilities into account.
Capture the relationship between your environment and your abilities.
Action-specific perception
Refers to visual information used to control an ongoing movement
Involves complex and precise coordination of incoming visual information with outflowing muscle commands
Visual feedback
involved in planning reach movements
Medial intraparietal area (MIP)
involved in grasping movements.
Anterior intraparietal area (AIP)
involved in the control of eye movements, including intended eye movements; an analogous region exists in the human brain
Lateral intraparietal area (LIP)
How many cycles in a unit of time (measured in Hertz(Hz))
inverse of wavelength
Human hearing ranges from 20 to 20,000 HZ
Frequency/pitch
-We are sensitive to a very wide range of sound ___ between threshold for detection and threshold for pain
-If we wish to talk about sound pressure efficiently, we need a simple unit of measurement
-For this reason the decibel unit was developed
-This unit is unusual in that it is not an absolute value, but a ratio of two sound levels
(why use ratios? - recall that ratios may better describe our ability to discriminate sensory stimuli
Amplitude & Loudness
Curve showing the amplitude of tones at different frequencies that sound about equally loud
Equal loudness contour
A mathematical procedure for decomposing a complex waveform into a collection of sine waves with various frequencies and amplitudes.
Fourier analysis
A unit of loudness
Phon
Quality of the sound
consequence of the complexity of the wave
Timbre, Waveform or Complexity
A depiction of the amplitudes at all frequencies that make up a complex waveform.
Fourier spectrum
The frequency of the lowest-frequency component of a complex waveform; determines the perceived pitch of the sound.
Fundamental frequency
the auditory analogue of the retina
Is the site of neural transduction
Rests on the basilar membrane
Contains the hair cell receptors
The Organ of Corti:
The sense organs used to produce neural signals carrying information about
balance and acceleration;
includes the semicircular canals and the otolith organs.
vestibular system
Part of the vestibular system; three mutually perpendicular hollow curved tubes in the
skull filled with endolymph; responsible for singling head rotation.
semicircular canals
A tube connecting the middle ear and the top part of the throat; normally closed but can be briefly opened ( e. g., by swallowing or yawning) to equalize the air pressure in the middle ear with the air pressure outside.
Eustachian tube
converts air pressure changes into mechanical vibrations
Tympanic membrane
Funnels and modulates incoming sounds
resonant frequency – 2000 - 5000 Hz
Auditory canal
A component frequency of a complex waveform that, for periodic sounds, is an integer multiple of the fundamental frequency
Harmonic
The difference in sound quality between two sounds with the same pitch and loudness; for complex periodic sounds, is mainly due to differences in the relative amplitudes of the sounds’ overtones or harmonics; the perceptual dimension of sound that is related to the physical dimension of waveform.
Timbre
reducing sensitivity to pain by modulating the intensity of pain signals
Analgesia
Body map on the cortex shows more cortical space allocated to parts of the body that are responsible for detail – cortical magnification
homunculus
