HPS111 Lecture Notes - Lecture 6: Retina, Response Bias, Aerial Perspective
WEEK 6: Sensation and perception
Introduction
- Mind and behaviour
- Appropriates thoughts and feeling can be the difference between life and death
- Sensations
- Information reduces uncertainty
- Central to what it means to be a thinking organism
Defining
- Sensation is : awareness resulting from the stimulation of a sense organ
- Perception is : the organization and interpretation of sensations
- Some suggests sensation describes physical and perception as psychological
- Sensory transduction- exclusively sensory
- Its so hard to be differentiate
Psychophysics
- Vaber and Fekner measured basic things, how sensitive we are, absolute threshold
- Can also relate to time it takes
- Sped v time,
- Have different threshold
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- The difference threshold interesting properties
- Vaber fekners law:
oThe ratio of the increment threshold to the background level is a constant. Ie : the
amount of difference in intensity the just noticeable difference is not fixed constant
proportion against baseline which the comparison is ma
- If k is 2 the just noticeable difference but be 20% - 120 if its 100
Signal detection theory
- Decision making too, how your feel whats at stake
- Cognitive component
- Disentangles two independent performance sensory sensitivity , cognitive bias
- Whats more important sensitivity or bias
- Combination of sensation and decision making
- How do you respond if there is nothing there
- Not present anything at all- mistakes, false alarms responding yes when there is no stimulus,
- Combining hit rate and false alarm rate.
- It depends on whats important (like sensing cancer- false alarm better than not seeing it)
Sensory transduction
- The source of information about our environment (some sought of energy)
- Electro chemical activity in neurons must be translated
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- The conversion of sensory information from the environment into electrochemical activity
- Receptor types
oSimple receptors: free nerve ending that are simply exposed to the environment (eg
pain and touch receptors on skin)- electrochemical “neural impulse” which is
communicated
oEncapsulated receptors: normal but coated nerve ending that are more specifically
sensitive (specialised)
oSpecialised receptors: nerves with dendrites specialised to detect specific types of
information (light, smell, sound) (special sensory organs)
- Why because we found it necessary to excel in a special domain
Vision
- Light is what we see wave length and amplitude
Receptors
- Rods and cones (curved)
- Light causes these cell to changes its electrical potential
- Cones have specialsed for different types of light (blue, green or red)
- The provide a highe resolution imaged
- Rods are sensitive to light, flickering light
- Used at night or out the corner
- Light is refracted by the cornea and enters through pupil and focused by the lens which focuses
the light on the retina (can adjust its thickness (accommodation))
- Light reaching rods and cones is transduced
- Important because sense signal to ganglion cell which axon is the optic nerve
- Information transmits via the optic nerve to the thalamus
- The thalamus routes information the visual cortex in the occipital lobe
- The exist of the optic nerve from the eye leaves a blind spot
- Specialised cortical neruons combine multiple thalamic inputs to intergrate visual information
and detect visual features
Sensory disorders
- Problems with optic of the eye
- Myopia: near sightedness, can only focus on close objects, lens or cornea too strong, eyeball too
large
- Hyperopia: far sightedness, inable to focus on close objects, lens or cornea too weak, eyeball
tooo small
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Appropriates thoughts and feeling can be the difference between life and death. Central to what it means to be a thinking organism. Sensation is : awareness resulting from the stimulation of a sense organ. Perception is : the organization and interpretation of sensations. Some suggests sensation describes physical and perception as psychological. Vaber and fekner measured basic things, how sensitive we are, absolute threshold. Vaber fekners law: the ratio of the increment threshold to the background level is a constant. Ie : the amount of difference in intensity the just noticeable difference is not fixed constant proportion against baseline which the comparison is ma. If k is 2 the just noticeable difference but be 20% - 120 if its 100. Decision making too, how your feel whats at stake. Disentangles two independent performance sensory sensitivity , cognitive bias. How do you respond if there is nothing there.
