Perception Flashcards
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
Describe the location of photoreceptors
In the retina. About 120 million rods are distributed around each retina except in the very centre, the fovea.- an area of the retina where vision is the clearest. The absence of rods in the fovea decreases the sharpness of vision in reduced light but it can be overcome. Each retina only contains about 6 million cones which are densely packed in the fovea
Are rods or cones more sensitive?
Rods
Define blind spot
An area of the retina that contains neither cones or rods and therefore has no mechanism to detect light
Define receptive field
The region of the sensory surface that, when stimulated, causes a change in the firing rate of that neuron
Define tropographic visual organisation
Adjacent neurons process adjacent portions of the visual field
What is area v1?
The initial processing region of the primary visual cortex
What is visual form agnosia?
The inability to recognise objects by sight
What is the binding problem?
How features are linked together so that we see unified objects in our visual field
Define illusory conjunction
A perceptual mistake where features from multiple objects are incorrectly combined
Define feature integration theory
A theory that proposes that attention binds individual features together to comprise a composite stimulus
Define modularisation
the process of relatively encapsulated function
Define perpetual constancy
A perceptual principle stating that even as aspects of sensory signals change, perception remains consistence
What are monocular depth cues?
Aspects of a scene that yield information about depth when viewed with only one eye
