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Chapter 5

Chapter 5 Summarizing This is mostly what you need to know about the chapter and they are the most important things in the chapter.

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Dan Dolderman

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Chapter 5. Summarizing the principles of sensation, perception, and attention.
1. Stimuli must be coded to be understood by the brain: Stimuli reaching the receptors are
converted to neural impulses through the process of transduction.
2. Psychophysics relates stimulus to response: By studying how people respond to different
sensory level, scientists can determine thresholds and perceived changes (Signal-
detection theory). Our sensory systems are tuned to adapt to constant level of stimulation
and detect changes in our environment.
3. In gestation, taste buds are chemical detectors: The gustatory sense uses taste buds to
respond to the chemical substances producing basic sensation of sweet, sour, salty, and
bitter. The amount and concentration of taste buds vary individually.
4. In smell, the nasal cavity gathers particles of odour: Receptors in the olfactory epithelium
respond to chemicals and send signals to the olfactory bulb in the brain. Pheromones are
particular chemical signals linked to physiological responses in animals.
5. In touch, sensors in the skin detect pressure, temperature, and pain: The haptic sense
relies on tactile simulation to activate receptors temperature, sharp and dull pain, and
other sensation. Neural “gates” in the spinal cord also control pain.
6. In hearing, the ear is a sound-wave detector: The size and shape of sound wave activate
hair cell in the inner ear. The receptors respond depending on frequency of the sound
wave, timing, and the location of the activated receptors. Having two ears allows us to
locate the source of the sound.
7. In vision, the eye detects light waves: Receptors (rods and cones) in the retina detect
different forms of light waves. The lens helps the eye focus the stimulation on the retina
for near versus far objects. Colour is determined by wavelengths of light activating by
objects, or the mixing of wavelength of light.
8. Perception occurs in the brain: The primary auditory cortex handles hearing. Touch is
handled by the primary somatosensory cortex. Vision results from a complex series of
events in a variety of areas of the brain but primarily in the occipital lobe.
9. Object perception requires construction: By using the Gestalt principles of stimulus
organization, we are able to perceive our world. We use cues about similarity, proximity,
form, figure and background properties, and shading. Perception involves the dual
processes: bottom-up (sensory information) and top-down (brain organization).
10. Depth perception is important for location objects: The pattern of stimulation of an object
on each of the two retinas (biocular) informs the brain about depth. Pictorial (monocular)
cues use information from the appearance of objects relative to their surroundings to
inform about depth, as well as relative motion.
11. Size perception depends on distance perception Illusions of size can be created when the
retinal size conflicts with the known size of object in the visual field, such as with the
Ames, Ponzo, and moon illusions.
12. Motion perception as both internal and external cues: Motion detectors in the cortex
respond to stimulation. The perceptual system establishes a stable frame of reference and
relates object movement to it. Intervals of stimulation of repeated objects give the
impression of continuous movement.
13. Perceptual constancies are based on ratio relationship: Hermann von Helmholz felt that
experience provides ratio information about object in their surroundings to achieve
constancy. James Gibson felt the information was a primary, evolutionarily based aspect
of perception. The contemporary view is a blend of the two theories.
14. Visual attention is selective and serial: We process the elements and features of visual
stimulus simultaneously. Studies of brain-injured patients reveal that different areas of
the brain process different information.
15. Auditory attention allows selective listening: The cocktail party phenomenon
demonstrates how we readily shift attention to relevant auditory information.
16. Selective attention can operate at multiple stages of processing: The debate on selective
attention centres on when information is filtered or passed on for further processing.