Week 7 - Sensation and Perception

Question 1

What are sensory processes?

Answer 1

the responses of low-level mechanisms within a given modality which depend on the magnitude of stimulus, the adaptation state of the system, and the internal noise.

Question 2

What is perception?

Answer 2

the organisation, identification and interpretation of sensory information in order to represent and understand the environment.

Question 3

What is the law of specific nerve energies (Johannes Müller (1826))?

Answer 3

Each nerve fibre is activated primarily by a certain type of stimulus and each makes specific connections to structures in the central nervous system whose activity gives rise to specific sensations

Question 4

Which sensory systems rely on chemical stimulus?

Answer 4

smell and taste.

Question 5

What are the three Somatosensory systems?

Answer 5

Proprioception, exteroception, and interoception.

Question 6

What is proprioception?

Answer 6

skeletal muscle, joint capsule, skin. They enable us to have conscious awareness of the posture of the movements of our own body, in particular, the four limbs and the head.

Question 7

What is exteroception?

Answer 7

touch, contact, pressure, stroking, vibration. It also involves active motor components: striking, tapping, grasping, pressing. The sensory and motor components of touch are tightly connected anatomically in the brain and are important in guiding behaviour. Also includes thermal sense and pain.

Question 8

What is interoception?

Answer 8

the sense of the major organ systems of the body and its internal state. Although most of the events recorded by the receptors in the viscera do not become conscious sensations, the information conveyed by these receptors is crucial for regulating autonomic functions: cardiovascular, respiratory, digestive and renal.

Question 9

Sensory systems mediate what 4 attributes?

Answer 9

modality, intensity, location, and duration.

Question 10

What do the olfactory receptors do?

Answer 10

bind specific odorant molecules and depolarises (channels opening) the sensory nerve via a second messenger system.

Question 11

Why do submodalities exist?

Answer 11

because each class of receptors is not homogeneous but contains a variety of specialized receptors that respond to a limited range of stimulus energy.`

Question 12

What are tuning curves of sensory receptors?

Answer 12

measure the minimum amplitude of a stimulation needed to activate a sensory receptor over a range of stimulus energies.

Question 13

Spatial awareness involves what three distinct perceptual abilities?

Answer 13

1. Locating the site of stimulation on the body or the stimulus source in space.
2. Discriminating the size and shape of objects
3. Resolving the fine detail of the stimulus

Question 14

What determines the resolution of the visual image?

Answer 14

The density of sensory receptors in the retina and the size of the receptive field.

Question 15

Intensity of sensation is determined by?

Answer 15

The stimulus amplitude.

Question 16

The capacity of sensory systems to extract information about the magnitude of the stimulus is important for two aspects of the sensory discrimination:

Answer 16

1. Distinguishing among stimuli that differ only in strength (as opposed to those that differ in modality or location).
2. Evaluating stimulus amplitude

Question 17

About how many rods and cones are in the retina?

Answer 17

about 20 M of rods and 6 M of cones.

Question 18

What are rods?

Answer 18

Achromatic night vision, 1 type.

Question 19

What are cones?

Answer 19

Daytime achromatic and chromatic vision, 3 types:

1. Long-wavelength sensitive (L) cone / red sensor
2. Middle-wavelength sensitive (M) cone / green sensor
3. short-wavelength sensitive (S) cone/blue sensor

Question 20

What is the trichromatic theory?

Answer 20

All colours are made up of some mix of red, green and blue,

Question 21

The dorsal pathway is

Answer 21

extending to the posterior parietal cortex and is thought to be particularly involved in processing motion, depth, and spatial information.
Dorsal pathway is multifunctional: attention; eye movements; numerical calculation and spatial processing.

Question 22

Why do we know the trichromatic theory is not sufficient?

Answer 22

It cannot explain afterimages and certain colour combinations. Was followed by the chromatic system, which includes red, blue, yellow, and green.

Question 23

What is the ventral pathway?

Answer 23

extending to the inferior temporal cortex and is more concerned with form and colour.

Question 24

What happens in the inferior temporal cortex?

Answer 24

1- cells respond to meaningful objects – object recognition
2- damage produces visual agnosia
3- face recognition (fusiform gyrus- occipital face area - amygdala)

Question 25

What happens in the Middle Temporal Cortex- Medial Superior Temporal Cortex?

Answer 25

1- cells in MT respond to motion /speed – photos implying motion
2- cells in MST respond to contraction/extension/rotation
3- damage produces motion blindness