Lecture 1 - Problems with Perception Flashcards
(36 cards)
What is the purpose of perception?
To collect information and make sense of the world.
FINISH the SENTENCE: Visual and auditory _ creates _ to form _ perceptions.
Noise, distractions, accurate
What happens to sensory signals when the environment is noisy or crowded?
It’s challenging to encode and process sensory information. Signals are drowned out.
TRUE or FALSE: Sensory systems are unlimited and cannot become overloaded.
FALSE: Sensory systems are limited and can become overloaded.
How do sensory systems work?
Sensory systems act as filters for environmental information or input.
Give an example of a sensory system. Can we process more than what the system lets in?
Wavelengths of light are filtered by three types of cones (red, blue, green), allowing colour vision.
We can’t process more than the information we have been given - only what the filter lets in. As such, we do not process all the visual spectrum simultaneously.
Is this filtering useful or detrimental?
Useful. Filtering allows us to organise only the relevant and necessary sensory information.
Which two lobes primarily process perception, and what can disrupt the flow of information?
The occipital and temporal lobes. Information entering these areas can be disrupted by conditions of the environment.
FINISH THE SENTENCE: _ _ information can guide our perceptions through top-down informational processing.
Perception is a mix of both top-down and _.
Already known, bottom-up
TRUE or FALSE: Seeing is a faithful record. Our eyes work like a camera. The outside world is captured like on film. As such, the visual system is infallible, and we cannot be deceived.
FALSE: Seeing is not a faithful record. Our eyes do not work like cameras.
The eye and the brain must cooperate - we have to integrate already known knowledge and what we see to form images. As such, the visual system is vulnerable to error - this causes illusions, seeing elements that are not truly there.
How do we visually construct images?
To create a full image, we construct individual elements present in the environment and integrate them together, rather than capturing single components.
Give an example of how we construct images or visual records in the visual system. (5)
An image may first be perceived through its colour - encoded by retinal cones - and contrasts - determined by different spatial frequencies.
The image continues to be formed through the primary visual cortex and creates mental representations (i.e., certain signals from simple cells).
The full image is formed through higher order mechanisms, integrating all sensory information.
Is vision a passive process and rich in detail? How do we know an image is incorrect?
Vision is an active process and is lacking in detail.
We only notice if something is wrong about an image if we direct ourselves to its details.
Do we focus on all of the image or only on details? (3)
We focus only on the important details. Our visual system samples on a ‘need-to-see’ basis. Eye movements are goal directed.
Is imageless thought a myth or fact?
Imageless thought is a myth, although conditions such as aphantasia exist. This is where the individual cannot visualise mental imagery.
Under normal circumstances, we can recreate scenes and imagine different scenarios through mental imagery.
We use the same areas of the brain in creating mental imagery as visual perception.
Do people with aphantasia or colour blindness realise they have these conditions? Why or why not?
They often do not. This is because their sensory systems have found ways to substitute processing in the absence of typical mechanisms.
TRUE or FALSE: The brain processes all sensory information simultaneously and in the same area.
FALSE. The brain separates and organises information into different sensory categories. This includes sound, colours, depth, etc.
What is the difference between lower level processes and higher level processes?
What can the brain be considered in considering this?
Lower level processes form images and perceptions, identifying individual elements and encoding them.
Higher level processes integrate this sensory information to construct the sensory experience.
The brain is a map that locates where different elements are processed/categorised/integrated.
Where does the visual system start?
The visual system starts at the eyes and the retina.
How many types of ganglion cells are there in the eye and what do they process?
There are 30 types of ganglion cells. These mainly process space and colour.
What are the three main types of ganglion cells? What does their size indicate?
The three main types of ganglion cells (in order of smallest to largest) are midget, bi-stratified, and parasol.
The larger the cell, the more visual information that can be processed.
The Lateral Geniculate Nucleus (LGN) has 6 layers. Describe the three sizes of these layers and where the LGN is located.
The 6 layers of the LGN are magnocellular, parvocellular, and koniocellular in order of size (largest to smallest).
Four layers receive parvocellular input. Two layers receive magnocellular input. The LGN is in the thalamus.
The Lateral Geniculate Nucleus sends input towards what system?
The LGN sends information to the Primary Visual Cortex - otherwise known as the Straite Cortex.
The primary visual cortex is separated into six layers. Each layer has different cells, and each functions differently.
What is the main function of V1 - the first layer of the primary visual cortex - and how does this section organise information?
V1 organises information through sorting colour contrast, achromatic contrast, ocular dominance, and orientation columns.
