What is sensation?
Sensation is the process by which sensory organs gather information and transmit it to the brain for initial processing.
What is perception?
Perception is the process by which the brain selects, organizes and interprets sensations.
What are the three basic principles that apply across all senses?
- There is no one-to-one correspondence between physical and psychological reality
- Sensation and perception are active, not passive
- Sensory and perceptual processes reflect the impact of adaptive pressures over the course of evolution
Vision
What is light?
Light is a form of electromagnetic radiation that the eye is sensitive to.
What are the two basic processes that occur in the eyes?
- Light is focused on the retina by the cornea, pupil and lens
- The retina transduces (converts into neural impulses) this visual image into a code that the brain can read
What are the two pathways that visual information travels along from the optic nerve?
- Visual information travels along the superior colliculus in the midbrain, which in humans is particularly involved in eye movements
- The other is the lateral geniculate nucleus in the thalamus and on to the visual cortex. Beyond the primary visual cortex, visual information flows along two pathways (‘what’ pathway and ‘where’ pathway).
What do the Young-Helmholtz or trichromatic theory and the opponent-process theory suggest?
→The Young-Helmholtz or trichromatic theory states that the eye contains three types of receptors that are most sensitive to wavelengths experienced in red, green or blue.
→The opponent-process theory suggests that the colours we experience reflect three antagonistic colour systems: a blue-yellow, red-green, and black-white system.
What is perceptual organization and what are the four aspects?
Perceptual organization integrates sensations into percepts, and locates them in space and preserves their meaning as the perceiver examines them from different vantage points.
Four aspects include: form perception, depth or distance perception, motion perception and perceptual constancy.
How does perceptual interpretation work?
Perceptual interpretation relies on both sensation and memory because the brain interprets current sensations based on past experience.
What is bottom-up and top-down processing?
→Bottom-up processing: emphasises the role of sensory data in shaping perception
→Top-down processing: emphasises the influence of prior experience on perception
What is transduction?
Transduction: is the process of converting stimulus information into neural impulses.
What is the absolute threshold?
The absolute threshold: is the minimum amount of energy needed for an observer to sense that a stimulus is present.
What is the difference threshold?
The difference threshold: is the lowest level of stimulation required to sense that a change in stimulation has occurred.
What is sensory adaptation?
Sensory adaptation: is the tendency of sensory systems to respond less to stimuli that continue without change.
