Deck 4: B: Sensation and Perception

Question 1

What is psychophysics? Describe and distinguish between the absolute threshold of a stimulus and the just noticeable difference (JND)by defining and giving an example of each.

Answer 1

Answers will vary but should include the following information for full credit.
--Psychophysics is the study of how we perceive sensory stimuli based on their physical characteristics.
--Absolute threshold of a stimulus is the lowest level of a stimulus we can detect on 50 percent of trials when that stimulus appears by itself.Imagine that a researcher fits us with a pair of headphones and places us in a quiet room.She asks repeatedly if we've heard one of many very faint tones.Detection isn't an all-or-none state of affairs,because human error increases as stimuli become weaker.
--Just noticeable difference (JND)is the smallest change in the intensity of a stimulus that we can detect.The JND is relevant to our ability to distinguish a stronger from a weaker stimulus,like a soft noise from a slightly louder noise.The stronger the stimulus,the bigger the change needed for a change in stimulus intensity to be noticeable-think of how much light we'd need to add to a brightly lit kitchen to notice an increase in illumination compared with the amount of light we'd need to add to a dark bedroom to notice a change in illumination.

Question 2

What is perceptual constancy? Explain and identify the three main types of perceptual constancies,including an example of each.

Answer 2

Answers will vary but should include the following information for full credit.
--The process by which we perceive stimuli consistently across varied conditions is perceptual constancy.There are several kinds of perceptual constancy-shape,size,and colour constancy.
--Shape constancy: we still see a door as a door whether it's completely shut,barely open,or more fully open,even though these shapes differ markedly from each other.
--Size constancy: our ability to perceive objects as the same size no matter how near or far away they are from us.When a friend walks away from us,her image becomes smaller.But we almost never realize this is happening,nor do we conclude that our friend is mysteriously shrinking.
--Colour constancy: is our ability to perceive colour consistently across different levels of illumination.Consider a group of firefighters dressed in bright yellow jackets.Their jackets look bright yellow even in very low levels of ambient light.That's because our perceptual apparatus evaluates the colour of an object in the context of background light and surrounding colours.

Question 3

Briefly describe the three theories of pitch perception.

Answer 3

Answers will vary but should include the following information for full credit.
--Place theory: a specific place along the basilar membrane (and also in the auditory cortex)matches a tone with a specific pitch;place theory accounts only for our perception of high-pitched tones,namely those from 5000 to 20 000 Hz.
--Frequency theory: the rate at which neurons fire action potentials faithfully reproduces the pitch.This method works well up to 100 Hz (low-pitched),because many neurons have maximal firing rates near that limit.
--Volley theory: a variation of frequency theory that works for tones between 100 and 5000 Hz (low-pitched).According to volley theory,sets of neurons fire at their highest rate,say 100 Hz,slightly out of sync with each other to reach overall rates up to 5000 Hz.

Question 4

How might a proponent of ESP use signal detection theory to explain the experimenter effect that interferes with demonstrating that ESP exists?

Question 5

Discuss why selective attention is sometimes beneficial and sometimes detrimental.

Question 6

Explain why food tastes different when we have a cold versus when we do not.

Question 7

What is synesthesia? Describe what it is,how it relates to sensation,and what some of the different forms of synesthesia are.

Question 8

Describe the general process of how light enters the eye and is transmitted to the brain to be perceived.

Question 9

Identify and describe three of the six main Gestalt principles of perception.

Question 10

Identify the three body senses and briefly describe each with respect to the receptors each uses and what parts of the body/brain are involved in this sense.

Question 11

Describe how an artist might make use of the monocular cues for depth perception to create a three-dimensional feel in a two-dimensional painting.