Perception and decision making & Color

Signal detection

Detection

method of limits

adaptive testing

method of constant stimuli

set of stimuli; participant indicated if noticed

works for all sensory systems: takes time

arbitrary threshold

ascending/descending series of stimuli

descending gives lower thresholds

focus on absolute threshold

stimuli hover around absolute treshold

Signal detection theory

mathematical

deduces individual sensitivity

testing

2 types

signal present

signal absent

possible outcomes

Hit

False alarm

correct negative

miss

probability distribution

X: sensory activity level

Y: likelihood of occurrences

ß-criterion used to make decisions

activity over ß: yes

below: no

Sensitivity

measured in d

can be calculated by overlap between hit/miss distributions

Color

Discrimination

difference threshold

derived from interval of uncertainty

Threshold = just noticeable difference

Webers law

sensitivity can be calculated using weber constant

difference threshold larger for larger standards

roughly linear

large = poor

colors & wavelength

500-575nm green

575-590nm yellow

450-490nm blue

590-620nm orange

400-450nm violet

620-700nm red

colors show different reflectance on objects

selective reflection

Trichromatic theory of color vision

3 types of receptors to detect color

mix of three receptors can create any color

by young & helmholtz

cone pigments

each responsive best to low middle or high nm

made from opsin & retinal

different structures in opsin for diff. spectra

metamerism

multiple combinations create the same color

Opponent-Process Theory of color vision

receptors are exited & inhibited by different wavelengths

3 mechanisms

Black(-) White (+)

Red(+) Green(-)

Blue(-) Yellow (+)

Opponent neurons found in retina & lateral geniculate nucleus

cause for afterimages

Trichromatic theory first, then opponent theory

perception of color depends on

wavelength to which the receptor fires most

arrangement ob inhibiting and exiting neurons

color deficiency

Dichromatism

anomalous trichromat

Monochromatism

unilateral diochromats

only affecting one eye

different mixing of wavelenghts

one detector malfunctioning

no color vision

Types

deuteranopia

tritianopia

protanopia

about the concept map

Sources

  1. Blake, R., & Sekuler, R. (2005). Perception (5th ed.). Boston, MA: McGraw-Hill. (20%)
  2. Coren, S., Ward, L.M., & Enns, J.T. (1999). Sensation and perception (5th ed.). New York, NY: Harcourt Brace. (50%)
    3.Goldstein, E.B. (2010). Sensation and perception (8th ed.). New York, NY: Wadsworth. (30%)