PSYA01H3 Lecture Notes - Lecture 8: Absolute Threshold, Neural Adaptation, Psychophysics
Chapter 4: Sensation and Perception at a Glance
Sensation and Perception (127-128)
- Sensation: The process of detecting external events with sense organs and turning those
stimuli into neural signals
- Perception: Involves attending to, organizing, and interpreting stimuli that we sense
- The raw sensation detected by the sensory organs are turned into information that the
brain can process through transduction: When specialized receptors transform the
physical energy of the outside world into neural impulses
- Doctrine of Specific Nerve Energies was introduced by German physiologist Johannes
Muller that the different senses are separated in the brain
- Sensory adaptation: The reduction of activity in sensory receptors with repeated
exposure to a stimuli
• EX. Sound of traffic becomes less intense after a few minutes of hearing it
Stimulus Thresholds (129-130)
- German physicist William Gustav was interested in vision
- Helped to create psychophysics: The field of study that explores how physical energy
such as light and sound and their intensity relate to psychological experiences
- Absolute threshold: The minimum amount of energy or quantity of a stimulus required
for it to be reliably detected at least 50% of the time it is presented
- Difference threshold: The smallest difference between stimuli that can be reliably
detected at least 50% of the time
- Weber’s law: States that the just noticeable difference between two stimuli changes as a
proportion of those stimuli
• Holding 50g of candy in your hand you might not notice if one gram is added
- Signal Detection Theory: States that whether a stimulus is perceived depends on both
the sensory experience and the judgment made by the subject. Theory requires two us to
examine two processes: a sensory process and a decision process
• An experimenter would present either a faint stimulus or no stimulus known as
sensory process
• Then the subject is asked whether or not a stimulus was actually presented known
as decision process
Priming and Subliminal Perception (131-132)
- Laboratory based studies use a technique called priming in which previous exposure to a
stimulus can influence that individuals later responses
- In subliminal experimenters present a word or an image for a fraction of a second and
then immediately after present another image known as the mask. The mask interferes
with the conscious perception of the “subliminal” stimulus (perceivers are unaware that
any stimulus appeared before the mask
Gestalt Principles of Perception (133)
- Gestalt psychology is an approach to perception that emphasizes that “the whole is
greater than the sum of its parts)
• Individual parts of an image have little meaning but when come together the
whole takes on a significant perceived form
Document Summary
Chapter 4: sensation and perception at a glance. Sensation: the process of detecting external events with sense organs and turning those stimuli into neural signals. Perception: involves attending to, organizing, and interpreting stimuli that we sense. The raw sensation detected by the sensory organs are turned into information that the brain can process through transduction: when specialized receptors transform the physical energy of the outside world into neural impulses. Doctrine of specific nerve energies was introduced by german physiologist johannes. Muller that the different senses are separated in the brain. Sensory adaptation: the reduction of activity in sensory receptors with repeated exposure to a stimuli: ex. Sound of traffic becomes less intense after a few minutes of hearing it. German physicist william gustav was interested in vision. Helped to create psychophysics: the field of study that explores how physical energy such as light and sound and their intensity relate to psychological experiences.
