Perception Flashcards
(37 cards)
Define perception
The organisation, identification and interpretation of a sensation in order to form a mental representation
Define sensation
Simple awareness due to the stimulation of a sense organs
Where are receptor cells found?
Organised into sensory organs or distributed through tissues such as skin and muscle
Describe the relationship between perception and receptor cells
- Perception depends on effects of external energy on the activity of specialised nerve cells
- Receptor cells transduce external injury into electrical signals, transmitted on to other nerve cells
Define synaesthesia
The perception experience of one sense that is evoked by another sense. Simulation of one sensory pathways leads to automatic, involuntary experiences in a second pathway
Synaesthesisa has a strong hereditary factor. Which chromosome is it linked with
X chromosome
Define absolute threshold
-Describes the relationship between the physical intensity of a stimuli and whether it is perceived or not. Minimum intensity needed to just barely detect a stimulus
Describe finding the absolute threshold
Observer presented with stimulus varying intensity. Each trial responds yes or no if they can detect it. E.g hearing test- absolute threshold as the loudness required for the listener to say they heard the tone in 50% of trials
What is the just noticeable difference?
The absolute threshold is useful for assessing how sensitive we are to faint stimuli but most everyday perception involves detecting stimuli well above absolute. JND is a way of measuring this different threshold. It is the minimal change in a stimulus that can just barely be detected
Describe finding the just noticeable difference
Observer presented repeatedly with a reference stimuli (fixed intensity) and a comparison stimuli (varies). Responds by saying whether the comparison stimulus appears more or less intense that the reference
What is Fechner’s law?
Perceived intensity of a stimulus increases in proportion to the logarithm of its physical intensity
Describe signal detection theory
Treats a stimulis as a signal that needs to be detected against a background fog noise. Noise is caused by random fluctuations in receptor cells and other neurons
Define modalities
Sensory brain regions that process different components of the perceptual world
Define transduction
What takes place when many sensors in the body convert physical signals from the environment into neural signals sent to the central nervous system. E.g light reflected from surfaces provide the eyes with information about the shape, colour, position of objects
Define psychophysics
Methods that measure the strength of a stimulus and the observers sensitivity to that stimulus.
Developed by Fechner
Define Weber’s law
The just noticeable difference of a stimulus is a constant proportion despite variations in intensity
Define signal detection theory
An observation that the response to a stimulus depends on a person’s sensitivity to the stimulus in the presence of noise and on a person’s response criterion
Define D prime
A statistic that gives a relatively pure measure of the observers sensitivity or ability to detect signals
Define sensory adaptation
Sensitivity to prolonged stimulation tends to decline over time as an organism adapts to current conditions
What is the retina?
Light sensitive tissue lining the back of the eyeball (light focused on the retina)
Define accommodation
The process by which the eye maintains a clear imagine on the retina
Define visual acuity
The ability to see fine detail
Define cones
Photoreceptors that detect colour, operate under normal daylight conditions and allow us to focus on fine details
Define rods
Photoreceptors that become active only under low light conditions for night vision
