Chapter 4

Question 1

Absolute threshold and Just Noticeable Difference

Answer 1

Absolute threshold: the lowest level of a stimulus that we can detect 50% of the time

Just noticeable difference: the smallest change in the intensity of a stimulus that we can detect
- The stronger the stimulus, the bigger the change in
intensity needed for us to notice it.

Question 2

Signal detection theory

Answer 2

Absolute thresholds hold under ideal conditions (e.g., no other stimuli present).

What happens when conditions are less than ideal?

Signal-to-noise ratio: harder to detect a signal clearly as background noise increases.

Question 3

Sensory adaptation

Answer 3

Response to a stimulus is greatest when first detected.
Response decreases in strength with repeated exposure.
Adaptive response – WHY?
e.g. Clothes, ticking of clocks, sound of AC, hum of fridge.

Question 4

Bottom-up vs. Top-Down processing

Answer 4

Bottom-up processing
- Begins with sensory data and goes up to the brain’s
integration of this information.
- Data-driven, requires no previous knowledge or
learning

Top-down processing
- Works from the general to the specific— big picture
to fine details.
- Previous experiences influences the information you
gather through your senses.

Question 5

Synesthesia and the McGurk effect

Answer 5

McGurk effect: we integrate auditory and visual information when processing spoken language.

Question 6

Inattentional blindness

Answer 6

Inattentional blindness: failure to detect stimuli in plain sight when our attention is focused on something else
- Almost half of participants failed to notice the gorilla.

Question 7

Gestalt Principles

Answer 7

1. Figure/Ground
2. Similarity
3. Proximity
4. Closure
5. Good Continuation (Continuity)
6. Symmetry or Order

Question 8

Feature detection cells

Answer 8

Feature detectors are individual neurons—or groups of neurons—in the brain which code for perceptually significant stimuli