Lab 4

Question 1

How does sensation begin?

Answer 1

With a detectable stimulus

Question 2

Fechner

Answer 2

the concept of the threshold

Question 3

Absolute threshold

Answer 3

where the stimulus is detected 50% of the time

Question 4

Just noticeable difference (JND):

Answer 4

smallest difference detectable

Question 5

Weber’s law

Answer 5

size of JND proportional to size of initial stimulus

Question 6

Psychophysical Scaling

Answer 6

Fechner’s Law = size of perceptual experience is proportional to the number of
JND’s that the stimulus is above the absolute threshold. Fechner’s Law tells us that our perception of intensity isn’t just based on the absolute amount of stimulus, but how many JNDs it’s above the absolute threshold. So, the more JNDs above that threshold, the stronger the perception.

Question 7

What is sensation

Answer 7

Stimulation of sensory organs

Question 8

Key Components of Signal Detection Theory:

Answer 8

Sensory Processes (Sensitivity):
This refers to how well you can detect a signal (stimulus) in the presence of noise.
Decision Processes (Bias):
Decision-making involves bias or the threshold you set for deciding whether you detected the signal or not. This is influenced by factors like your expectations, experience
Hit: Signal present and you detect it.
Miss: Signal present but you fail to detect it.
False alarms: Signal absent, but you mistakenly think it’s present.
Correct Rejection: Signal absent and you correctly identify that there is no signal.

Question 9

Perception is for

Answer 9

perceiving forms, patterns and objects

Question 10

Bottom-up Processing:

Answer 10

According to Feature Detection Theory, people detect specific elements in stimuli and
build them up into recognizable forms

Question 11

Top-down Processing

Answer 11

Form perception involves top-down processing: Formulating a perceptual
hypothesis of the stimulus as a whole, and then select and examining features to see if you’re right

Question 12

illusion

Answer 12

distortion of the senses, revealing how the brain normally organizes and interprets sensory
stimulation

Question 13

Perceptual Set Theory

Answer 13

explains that when our expectations influence our perceptions we have a
tendency to perceive or notice some aspects of the available sensory data and ignore others. Stresses the idea
of perception as an active process. Perceptual Sets demonstrate that the same visual stimulus can result in
very different perceptions

Question 14

Optical Illusions

Answer 14

discrepancy between visual appearance and physical reality

Question 15

IV, DV, CV

Answer 15

IV: 12 Comparator line lengths (constant stimuli)
DV: Probability of choosing “longer” and Skill Time
CV: Size of the Reference Line, Progressive error, Random error

Question 16

Hypothesis

Answer 16

The closer the comparator line in length is to the reference line, the harder it will be to judge which is longer, and the longer the decision will take in seconds due to the Muller-Lyer illusion.

Question 17

Absolute Threshold value

Answer 17

what length do you call LARGER half the time? where does the
“Larger” line cross the 50% line.

Question 18

Experimental question

Answer 18

What is the effect of the physical size of the line (X) on the probability of saying LARGER (Y) while controlling
for progressive error and random error (Z)?