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Question 1

Sensation

Answer 1

The process by which the sense organs gather information about the environment and transmit the information to the brain for initial processing

Question 2

Perception

Answer 2

The process by which the brain selects, organises and interprets sensations

Question 3

3 broad principles S&P

Answer 3

1. There is no one-to-one correspondence between physical and psychological reality; measuring this is the realm of psychophysics.
2. Sensation and perception are active processes.
3. Sensation and perception are adaptive (facilitation of survival and reproduction).

Question 4

Features common to all sensory systems (1 & 2)

Answer 4

1. Each sensory system has sensory receptors that:
   - Detect physical energy (e.g., light waves)
   - Translate physical stimulation into neural signals (transduction)
2. Each sensory system requires a minimum amount of energy to activate the system (threshold).
   All senses have threshold below which a person does not sense anything despite external stimulation.

Question 5

Features common to all sensory systems (3, 4 & 5)

Answer 5

3. Sensation requires constant decision making
4. Sensing the world requires the ability to detect
   changes in stimulation.
5. Efficient sensory processing requires “turning down the volume” or suppressing redundant information

Question 6

Absolute threshold

Answer 6

Sensory systems require a minimum amount of energy for activation.
Thresholds vary from person to person and situation to situation. Why? “Noise”!
• External noise
• Internal noise: random firing of neurons
• Internal noise: psychological factors such as expectation, motivation, stress, fatigue

Question 7

Signal detection theory

Answer 7

making a decision about the presence or absence of a signal within the background noise due to
Initial sensory process
Decision process

Question 8

Initial sensory process

Answer 8

the observer’s sensitivity to the stimulus

Question 9

Decision process

Answer 9

the observer’s response bias (readiness to report detecting a stimulus when not certain)

Question 10

Difference thresholds

Answer 10

The lowest level of stimulation required to sense that a change in stimulation has occurred.
Just noticeable difference (JND)
Weber’s law
Fechner’s law

Question 11

Weber’s law

Answer 11

Regardless of the magnitude of two stimuli, the second must differ by a constant proportion from the first to be perceived as different.

Question 12

Fechner’s law

Answer 12

The magnitude of a stimulus grows logarithmically as the subjective experience of intensity grows arithmetically.

Question 13

Steven’s power law

Answer 13

As the perceived intensity of a stimulus grows arithmetically, the actual magnitude of the stimulus grows exponentially (squared, cubed, etc.)

Question 14

Vision transduction

Answer 14

• Sensation requires converting energy in the world into neural signals.
• Specialized cells known as sensory receptors transform energy into neural impulses that can be interpreted by the brain.
• Transduction: the process of converting physical energy or stimulus information into neural impulses.

Question 15

Retina

Answer 15

At the back of the eye, has photoreceptors (rods and cones) that traduce light into electrochemical signals (action potentials) when struck by light waves

Question 16

Pupillary response

Answer 16

Pupil dilates or contracts:
- To changes in ambient lighting
- Emotion, motivation, arousal
Expansion of pupil is relatively slow however contraction is very quick
As pupil dilates, more light and therefore information is let in

Question 17

Rods

Answer 17

Lower activation threshold, more sensitive so less light to activate
Cannot distinguish colour, not sensitive to the wavelength: linked to seeing in the dark however not colour
Located majority in the periphery: when star gazing look to the side of the star to line up the light with the side of your eye (where the rods are located)
Activated in between blue and green cones (450~600)

Question 18

Cones

Answer 18

Higher activation threshold, less sensitive for light so require more photons fro activation
Located majority in the centre of the retina called the fovea
Responsible for detailed vision - why you cannot read in low light
Respond to wavelength therefore give us the ability to see colour
Cones=Colour=Centre

Question 19

Response to short wavelengths

Answer 19

Blue cones as shorter wavelengths produce the colour blue

Activated before 400nm until around 500nm

Question 20

Response to middle wavelengths

Answer 20

Green cones as medium wavelengths produce the colour green

Activated at around 475nm until around 650nm

Question 21

Response to long wavelengths

Answer 21

Red cones as longer wavelengths produce the colour red

Activated at around 550nm to around 725nm

Question 22

The law of common fate states

Answer 22

Things that are moving in the same direction will be grouped together
For example, dots moving in the same direction are perceived as a group of dots moving together.

Question 23

Retinal disparity

Answer 23

differences between the two retinal images of the same scene – is a binocular depth cue
The greater the disparity of an object, the further away the object is perceived to be. Linear perspective, interposition and familiar size are all examples of monocular depth cues

Question 24

Top down processes

Answer 24

include expectations, motivations and knowledge

Question 25

Bottom up processes

Answer 25

include sensations, which are based on physical data from the environment

Question 26

Combination of top down and bottom up processes

Answer 26

The combined influence of top-down and bottom-up processes on perception are evident in illusions, where the physical properties of the stimulus do not match the perceived properties of the stimulus.