Chapter 5 Sensory, Attentional, and Perceptual Processes | class 11th | ncert quick revision notes psychology

Sensory, Attentional And Perceptual Processes – Notes for Class 11 Psychology

• We know our environment in particular and the world at large through our sense organs. The information collected by our sense organs is basis of our cognition. The whole phenomena of cognitive functioning is determined by sensation, attention and perception. Sensation refers to the stimulation of a receptor (e.g., eyes) rather than the experience (e.g., seeing i.e. perception). Attention refers to the tendency of an organism to focus on selected features of the environment. Perception is a process by which information in the environment is transformed into an experience.

I. External stimuli are received through specialized sensory receptor cells.
(A) Sense organs receive stimuli, convert sensory energy into neural impulses, and send neural messages to the brain for interpretation.
(B) Psychophysics is the field of psychology that studies the relationships between physical stimuli and psychological sensations and perceptions.
II. The sense organs of sight transduce light energy.
(A) The intensity of light waves largely determines brightness, while the wavelength (frequency) largely determines colour.
(B) The eye, working much like a camera, is the primary sense organ for seeing.
1. Light enters the eye through the cornea (with the iris regulating the size of the pupil) and the lens into the retina.
2. Rods and cdnes convert light waves into neural impulses for transportation to the brain.
3. The 125 million rods, located throughout the retina except for the fovea, are active in peripheral vision and vision in dim light, but they do not play a role in colour vision.
4. The 6 million cones clustered mostly near the fovea code information for colour.
5. Both trichromatic theory and opponent-process theory are helpful in understanding colour vision.
III. The sense of hearing detects sound waves.
(A) The frequency of sound waves determines pitch, while the intensity determines loudness.
(B) The ear is the primary sense organ for hearing.
(C) Sound waves vibrate the eardrum, which is connected to a series of three movable bones (hammer, anvil, stirrup) in the midDiffemtial thresholde ear.
(D) The inner ear, containing the cochlea and the organ of Corti, transduces the sound wave energy into neural impulses for transportation to the brain.
IV. Chemical senses respond to chemicals rather than to energy in the environment.
(A) In the sense of taste, chemicals produce the perception of qualities of sweet, sour, bitter, and salty.
(B) In the sense of smell, chemicals produce the perception of odours.
V. Internal stimuli are also received by the sensory system.
(A) The vestibular organ provides information about body orientation, while the kinesthetic sense reports bodily position and movement.
(B) The various skin senses can detect pressure, temperature, and pain.
1. Two sensations of pain reach the brain at slightly different times because they travel on different neural pathways.
(a) The first sensation reaches the somatosensory area quickly on myelinated neurons.
(b) The more emotional type of pain reaches the limbic system more slowly on unmyelinated neurons.

Word That Matter

1. Absolute threshold : The minimum intensity necessary for a stimulus to be detected.
2. After images : A visual image that persists after a stimulus is removed.
3. Binocular cues : Depth cues, such as retinal disparity and convergence, that depend on the use of two eyes.
4. Bottom-up processing : In form perception, progression from individual elements to
the whole.
5. Cochlea : The fluid-filled, coiled tunnel in the inner ear that contains the receptors for hearing.
6. Cones : Specialised visual receptors that play a key role in daylight vision and colour vision.
7. Dark adaptation : The process in which the eyes become more sensitive to light in low illumination.
8. Depth perception : The perception of the distance of an object from the observer or the distance from front to back of a solid object.
9. Difference threshold : The minimum difference between a pair of stimuli that can be perceived.
10. Divided attention : The process by which attention is split between two or more sets of stimuli.
11. Eustachian tube : Passage that connects the middle ear to the throat and allows release of pressure.
12. Gestalt: An organized whole, Gestalt psychologists emphasise our tendency to integrate pieces of information into meaningful wholes.
13. Lightadaptationr : Theadjustmentoftherodsandconesintheeyeto changes in illumination.
14. Loudness : The perception of a sound wave’s amplitude.
15. Monocular cues : Visual cues from one eye only.
16. Organ of corti : Structure on the surface of the basilar membrane that contains the receptor cells for hearing.
17. Perceptual constancy : The ability, in perception, to draw similar inferences about the world from different patterns of sensory activity (e.g., a person seen from many different angles is still perceived as the same person).
18. Phi phenomenon : The illusion of movement created by presenting visual stimuli in rapid succession.
19. Pitch : The perceptual interpretation of a sound’s frequency.
20. Primary colours: A set of three colours, i.e. red, green, and blue, when mixed in unequal amounts can produce any colour.
21. Retina: Layer of cells at the back of the eye containing photoreceptors.
22. Rods : Specialised visual receptors that play a key role in night vision and peripheral vision.
23. Selective attention : The focusing of conscious awareness on a particular stimulus.
24. Timbre : The characteristic quality of a tone produced by the combination of overtones heard along with the pure tone.
25. Top-down processing : In form perception, a progression from the whole to the elements.
26. Visual illusions: Physical stimuli that consistently produce errors in perception.
27. Wavelength: The distance from the peak of one light or sound wave to the peak of the next.