PSY 001 Lecture Notes - Lecture 7: Detection Theory, Absolute Threshold, Sound Energy
12 Jun 2018
School
Department
Course
Professor
Class 5 – Sensation and Perception
Jadzia Wray
Definition
- Sensation – the initial info gathering and recording by the sensory structures (taste, see, hear,
touch and smell)
- Perception – the interpretation of sensory info by the brain
5 Senses
- Vision: sight/ detection of light stimulus
- Audition: detection of sound energy/ vibration
- Olfaction: smell, chemical detection in the air
- Gustation: taste, chemical detection on tongue
- Somatosensation: detection of physical stimulation
Psychophysics
- Psychophysics - relationship between the physical world and the psychological world (how bright
does a light have to be for us to notice it?
- How much of a stimulus is needed for us to detect it?
- Absolute threshold – the minimum amount of energy in a sensory stimulus detected 50% of the
time
o “uliial essagig ad proessig does’t happen, but our brain can detect sensory
info without our conscious awareness
- How do we detect signals?
o Ability to detect things depends on you and how you detect things at that moment
- Signal detection theory – a theory that assumes that the detection of faint sensory stimuli
depeds ot ol upo a perso’s phsiologial sesitiit to a stiulus ut also upo his
decision criterion for detection, which is based on nonsensory factors.
- How do we detect differences between stimulus?
o Difference threshold (or noticeable difference) – the minimum difference between two
sensory stimuli detected 50% of the time.
What do we see?
- Light is electromagnetic radiation travelling in waves
- We only see a small part of the whole electromagnetic spectrum
How do we see and hear?
Sound:
- Wavelength – distance in one cycle of a wave (distance from peak to peak)
- Amplitude – the aout of eerg i a a ad it’s itesit the height of the ae
- Frequency – the number of times the waveform cycles in one second
find more resources at oneclass.com
find more resources at oneclass.com
Vision:
- Amplitude – brightness. Lower amplitude will show dull colors and higher amplitude will show
brighter colors
- Frequency – hue, short waves are blueish and long waves are reddish
- Short wavelengths = high frequency = blueish colors, high pitched sounds
- Long wavelengths = low frequency = reddish colors, low-pitched sounds
How do we see
- The first step is transduction, when the physical energy converts into neural signals that the
brain can understand
- Retina:
o Ganglion cells
o Bipolar cells
o Receptor cells
▪ Rods – responsible for dim light and achromatic (colorless) vision (for black and
white, do not distinguish colors, sensitive to light)
▪ Cones – responsible for bright light and color vision (for colors, distinguish
colors, not sensitive to light)
o Fovea – a tiny pit in the center of the retina filled with cones
- Need to know: Cornea (lets light into the eye), iris, pupil, lens, optic nerve, retina
How do we see?
- Farsightedness – difficulty viewing objects close to us because the light waves from distant
objects come into focus in front of the retina and blurs the vision
- Nearsightedness – difficulty viewing objects far from us because the light waves from nearby
objects come into focus in front of the retina and blur the vision
Color Theories:
- Trichromatic theory (3 cones have different colors and they interact) – there are three types of
cones, each only activated by wavelength ranges of light corresponding roughly to blue, green,
and red. All of the various colors that we can see are mixtures of various levels of activation of
the 3 types of color. If all 3 are activated, we see white.
- Opponent-process theory of color vision – there are 3 opponent-process cell systems (red-
green, blue-yellow, and black-white) that process color info after it has been processed by the
cones. The colors in each system oppose one another in that if one color is stimulated, the
other is inhibited. (pairs of colors used)
- Composite theory/dual process theory – color info is processed by the cones according to the
trichromatic theory, but color info is processed at the post-receptor cell level according to the
opponent-process theory
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Sensation the initial info gathering and recording by the sensory structures (taste, see, hear, touch and smell) Perception the interpretation of sensory info by the brain. Olfaction: smell, chemical detection in the air. Absolute threshold the minimum amount of energy in a sensory stimulus detected 50% of the time: u(cid:271)li(cid:373)i(cid:374)al (cid:373)essagi(cid:374)g a(cid:374)d pro(cid:272)essi(cid:374)g does(cid:374)"t happen, but our brain can detect sensory info without our conscious awareness. How do we detect signals: ability to detect things depends on you and how you detect things at that moment. How do we detect differences between stimulus: difference threshold (or noticeable difference) the minimum difference between two sensory stimuli detected 50% of the time. We only see a small part of the whole electromagnetic spectrum. Wavelength distance in one cycle of a wave (distance from peak to peak) Amplitude the a(cid:373)ou(cid:374)t of e(cid:374)erg(cid:455) i(cid:374) a (cid:449)a(cid:455) a(cid:374)d it"s i(cid:374)te(cid:374)sit(cid:455) (cid:894)the height of the (cid:449)a(cid:448)e(cid:895)
