Chapter 2.1

Question 1

What is the difference between distal and proximal stimuli

Answer 1

Proximal

• > directly affect sensory receptors
• > inform the observer about the presence of distal stimuli
• > eg; photoreceptors respond to light

Distal

• > stimuli that originate outside the body
• > they are part of the outside world
• > eg; campfire

Question 2

What relationship does psychophysics look at

Answer 2

• it looks at the relationship between:
• > physical nature of stimuli and
• > sensations/perceptions that these stimuli evoke

Question 3

What is a threshold an example of? What does it state

Answer 3

-threshold indicates the minimum amount of a stimulus that renders a difference in perception

Question 4

What are the three types of thresholds

Answer 4

1) Absolute threshold
2) Threshold of conscious perception
3) Difference Threshold

Question 5

What is the absolute threshold? Is it a threshold in sensation or perception

Answer 5

• it is the minimum stimulus energy that is needed to activate the sensory system
• > it has to do with sensation

-it has to do with how bright, loud, or intense a stimulus must be before it is sensed

Question 6

What is the threshold of conscious perception? What kind of stimuli does it refer to? Do these stimuli arrive at the central nervous system? Are they transcuded?

Answer 6

• it is referred to stimuli that reach the central nervous system
• > but that are not perceived
• > stimuli is too subtle to demand our attention
• > or too brief of a duration for the brain to fully process it
• this is where the term subliminal comes in
• > stimuli that are below a given threshold
• > they arrive at the CNS and are transduced
• > but do not reach higher-order brain regions that control attention and consciousness

Question 7

What is psychophysical discrimination testing and what theory of threshold does it refer to?

Answer 7

• a participant is presented with one stimulus
• the participant is then presented with another stimulus and is asked if there is a difference
• > this goes on for many stimuli
• > the difference between the original and current stimulus is increased until the participant reports a difference

-psychophysical discrimination testing refers to the theory of threshold of conscious perception

Question 8

What does the difference threshold or just noticeable difference refer to

Answer 8

• it refers to the minimum difference

- >in magnitude between two stimuli before one can perceive the difference

Question 9

What is the Weber’s law

Answer 9

• there is a constant ratio between change in stimulus needed to produce a just noticeable difference
• > and the magnitude of the original stimulus
• therefore, to discriminate a stimuli
• > the difference between the original and the new stimuli must be greater than the jnd

Question 10

What does signal detection theory say perception can be affected by

Answer 10

• perception can be affected by:
• > nonsensory factors
• > such as experiences, motives and expectations

-change of stimuli depends on both internal and external factors

Question 11

How can signal detection theory allows us to explore response bias

Answer 11

• response bias refers to the tendency of subjects to respond to a stimulus in a particular way
• > due to nonsensory factors

Question 12

Describe the signal detection theory experiment that exposes response bias

Answer 12

• there are many trials
• trials in which stimuli are presented are catch trials
• trials in which stimuli are not presented are noise trials
• > after each trial, participants indicate whether the stimuli was presented or not
• hits= subject correctly perceives stimuli to be there
• miss=subject fails to perceive a given signal
• false alarm= subject says signals is there but none was given
• correct negative= subject correctly identifies that no signal was given

-significant proportion of misses or false alarms given an indication of response bias

Question 13

What is adaptation? Can adaptation have a physiological and a psychological component?

Answer 13

• adaptation is a way for our body to focus our attention to the more relevant stimuli
• > which are usually the changes in the environment around us
• it does have a physiological component(sensory) and a psychological component(perceptual)
• > eg; we adapt to cold water and it does not seem cold anymore(psychological)
• > pupils of eyes dilate in the dark(physiological adaptation)