Lecture 2 - Sensation 1

Question 1

What is Sensation?

Answer 1

The detection of external stimuli and the transmission of this information to the brain

Question 2

What is Perception?

Answer 2

The processing, organization, and interpretation of sensory signals - not necessarily conscious interpretation

Question 3

What is Bottom-Up Processing?

Answer 3

Perception based on the physical features of the stimulus

Question 4

What is Top-Down Processing?

Answer 4

How knowledge, expectations, or past experiences shape the interpretation of sensory information

Question 5

What is the difference between Sensation vs Perception?

Answer 5

The sensory information provided is
relatively constant (Sensation)
BUT
What is seen/perceived is very
variable (Perception)

Question 6

What is Sensory Coding?

Answer 6

Sensory receptors translate the physical properties of stimuli into patterns of neural impulses.

Question 7

What is Transduction?

Answer 7

The process by which sensory stimuli are converted to signals the brain can interpret

Question 8

What type of information does the brain need about a stimulus to perform transduction?

Answer 8

The brain needs qualitative and quantitative information about a stimulus.
> Qualitative information consists of the most basic qualities of a stimulus.
> Quantitative information consists of the degree, or magnitude.

Question 9

How does the brain know what the neural activity indicates (e.g., light, pain etc)?

Answer 9

Anatomical Coding and Temporal Coding

Question 10

What is Anatomical Coding?

Answer 10

The receptors (e.g., in the eye, ear etc) are connected to specific parts of the brain - when those parts of the brain are activated, the source of stimulation is clear
» sensations are coded by what is active

Question 11

What is Temporal Coding?

Answer 11

Different stimulation gives rise to different rates of activity in the receptor - e.g., When bright vs low light
» intensity of sensation is coded by rate of activity

Question 12

What is Qualitative Information in sensation?

Answer 12

Sensory receptors respond to qualitative differences by firing in different combinations

Question 13

What is Quantitative Information in sensation?

Answer 13

Sensory receptors respond to quantitative differences by firing at different rates

Question 14

What is the Absolute Threshold?

Answer 14

The minimum intensity of stimulation
that must occur before you experience a sensation.

Question 15

What is the Difference Threshold?

Answer 15

The minimum amount of change required for a person to detect a difference between two stimuli

Question 16

What is Weber’s Law?

Answer 16

The Just Noticeable Difference (jnd) between two stimuli is based on a proportion of the original stimulus rather than on a fixed amount of difference

E.g. if A = 100g and B = 105g, the JND = 5g
If A = 200g and B = 210g, the JND = 10g
If A = 300g and B = 325g, the JND = 25g

Question 17

How to detect the Absolute Threshold?

Answer 17

The level of intensity at which participants correctly detect a stimulus on 50% of trials in which it is presented is the Absolute Threshold.

Question 18

What is the Just Noticeable Difference?

Answer 18

The smallest difference between two stimuli that is observable

Question 19

What is Signal Detection Theory (SDT)?

Answer 19

A theory of perception based on the idea that
the detection of a stimulus requires a judgment and is not an all-or nothing process

Question 20

How is Signal Detection Theory researched?

Answer 20

Signal detection research involves a series of trials in which a stimulus is presented in only some trials. In each trial, the participant must state whether he or she sensed the stimulus.

Question 21

What is Sensory Adaptation?

Answer 21

A decrease in sensitivity to a constant level of stimulation

If a stimulus is presented continuously, the responses of the sensory systems that detect it tend to diminish over time - when a continuous stimulus stops, the sensory systems usually respond strongly as well

Question 22

How many methods for threshold measurement are there?

Answer 22

Fechner originated 3 methods for threshold measurement; The method of limits, the method of constant stimuli, and the method of adjustment

Question 23

What does the Method of Limits record?

Answer 23

Difference or absolute thresholds

Question 24

What does the method of constant stimuli record?

Answer 24

Difference and absolute thresholds

Question 25

What does the method of adjustment record?

Answer 25

Difference thresholds

Question 26

How does the method of limits work?

Answer 26

Stimulus intensity is increased/decreased until the subject starts/stops sensing the stimulus

Question 27

How does the method of constant stimuli work?

Answer 27

Stimulus intensity is varied in fixed steps across a circumscribed range

Question 28

How does the method of adjustment work?

Answer 28

Stimulus intensity is changed by the observer until they see it differ or be indistinguishable from a comparison stimulus
> Stimuli either start the same and are changed to differ, or start different and are changed to be the same