Task 1 Flashcards
Measuring experiences
What is perception?
- depends on the properties of the sensory receptors
- when brain starts to interpret and recognize
- never ends
- not a copy of the environment
What is sensation?
- mechanical
- chemical (taste, smell, internal senses)
- light (vision)
Measuring perception
- approach
- psychophysical
- physiological
psychophysical: measures the relationship between the stimuli and the behavioral response
physiological: measuring two relationships (stimuli - physiological responses; stimuli - behavioral responses)
Measuring perception
- thresholds
- Fechner (three main methods)
common idea: human perception can be a variable -> classical psychophysical methods
- method of constant stimuli: many stimuli, ranging to almost always perceivable, are presented one at a time (yes/no) (most accurate)
- method of limits: particular dimension of a stimulus, or different between two stimuli, varied incrementally until participant responds differently
- method of adjustment: subject controls change of the stimulus (fastest)
Measuring perception
- thresholds
- Weber
difference threshold: minimum difference that must exist between two stimuli before we can tell the difference between them
- difference is a percentage
- Weber fraction: 0.02
- Weber’s law: Weber fraction remains the same as the standard is changed (JND, just noticeable difference)
Measuring perception
- absolute threshold
minimum stimulus intensity that can just be detected
Measuring perception
- estimating magnitude
magnitude estimation: participant assigns values according to perceived magnitudes of the stimuli
Measuring perception
- estimating magnitude: Steven’s power law
Magnitude of subject sensation is proportional to stimulus magnitude raised to an exponent.
P=KS^n
P: perceived magnitude
K: constant
S: stimulus intensity
n: tells us something about way perceived magnitude (P) changes as intensity is increased
Measuring perception
- scaling methods: cross-modality matching
ability to match the intensities of sensations that come from different sensory modalities; this ability allows insight into sensory differences
Measuring perception
- Neuroimaging
EEG, MEG, CT, MRI, fMRI, BOLD, PET
How is perception influenced by external stimuli?
external influence -> oblique effect (better detail vision for verticals or horizontals compared to slanted lines)
The perceptual process
- Step 1
environmental stimulus
The perceptual process
- Step 2
- principle of transformation: stimuli and responses created by stimuli are transformed, or changed, between the environmental stimulus and perception
- principle of representation: everything a person perceives is based not on direct contact with stimuli but on representations of stimuli that are formed on the receptors and on activity in the person’s nervous system
- distal vs proximal stimulus
The perceptual process
- Step 3
Receptor Processes / Transduction
- transduction: transformation of one form of energy to another
- visual pigment: light-sensitive chemical that reacts to light
- sensory receptors: cells specialized to respond to environmental energy (rods and cones)
The perceptual process
- Step 4
Neural Processing - complex network of neurons (1) transmits signals from the receptors, through the retina, to the brain and (2) changes (or processes) these signals as they are transmitted - primary receiving areas: vision - occipital lobe hearing - temporal lobe skin senses - parietal lobe
