Unit 6 - Visual Perception Flashcards
What is meant by a sensation?
The effects of a stimulus on the sensory organs.
What is meant by perception?
The elaboration and interpretation of a sensory stimulus based on, for example, knowledge of how objects are structured where:
Elaboration in this context refers to the process of adding detail or complexity to a sensory stimulus, e.g., by using stored knowledge
Interpretation is the process by which the brain interprets and makes sense of sensory information received from the environment
What is the retina?
The internal surface of the eyes that consists of multiple layers, with some layers containing photoreceptors that convert light to neural signals, and others consisting of neurons themselves
What is a rod cell?
A type of photoreceptor specialised for low levels of light intensity, such as those found at night.
What is a cone cell?
A type of photoreceptor specialised for high levels of light intensity, such as those found during the day, and specialised for the detection of different wavelengths.
Where is the highest concentration of cones? What is this, and what is it responsible for?
In the fovea
A small, central pit in the retina responsible for sharp, detailed vision
What is the blind spot? In what proportion are rods and cones present there?
The point in which the optic nerve leaves the eye
Neither of them is present at all
What are bipolar cells? What do they create through their connections?
Cells that behave in on of two ways: detecting light areas on dark backgrounds (ON) or detecting dark areas on light backgrounds (OFF)
A receptive field
What is the receptive field?
The region of space that elicits a response from a given neuron
What are centre-surround cells used for?
Advanced processes like detecting edges and orientations
What is the dominant route to V1 from the eyes called? What does it go through? What is the function of this organ?
The geniculostriate pathway
The lateral geniculate nucleus (LGN)
Processing station
What are the Konio (K) layers? What is their functional specialisation?
Lies between P and M layers
Unclear
What is the primary visual cortex (V1)? What is its function regarding the spatial relationships found on the retina? What is another important function of it?
The first stage in visual processing in the cortex
Retaining them
Combining simple visual features into more complex ones.
What are the 6 layers of the LGN?
Upper four layers are called the parvocellular (P) layers, responsible for processing fine details and colour
Lower two layers are the magnocellular (M) layers, responsible for processing movement and larger, less detailed aspects of the visual field.
Four main transformations done by the V1 on visual information:
Distinguishing between light and dark
Distinguishing colours
Distinguishing edges (abrupt changes in brightness and/or colour)
Distinguishing depth
What are simple cells?
Cells in vision that respond to light in a particular orientation or points of light along that line
What are complex cells? How do their receptive fields compare to those of simple cells? Is stimulation required across the entire length of the receptive field? How can they be acquired?
Cells in vision that respond to light in a particular orientation but do not respond to single points of light
Larger receptive fields
Yes, it is.
By combining many simple cells
What are hypercomplex cells? How are they built?
Cells in vision that respond to particular orientations and particular lengths
From the responses of several complex cells
What does the path from the retinal ganglion cells to the suprachiasmatic nucleus involve?
Info about night or day feeding the biological clock
What are two alternative pathways through which visual information travels from the eye to different parts of the brain?
The Retinal Ganglion Cells to the Suprachiasmatic Nucleus
The Retinal Ganglion cells to the Superior Colliculus and Inferior Pulvinar
What is hemianopia? What damage is associated with it?
Cortical blindness restricted to one half of the visual field
Damage to primary visual cortex in one hemisphere
What does the path from the retinal ganglion cells to the superior colliculus and inferior pulvinar do?
Provides orienting stimuli for automatic body and eye movements, working faster than V1
What is quadrantanopia?
Cortical blindness restricted to a quarter of the visual field
What is the ventral stream in vision? Where does it start and end? What are its three specialisations?
A pathway extending from the occipital lobes to the temporal lobes
Object recognition, memory, semantics