Cognition 1 Basic Processes- Feature and Patterns
Big picture
● Looking at the machinery, the brain- tells us which bits do what and when
● Looking at what the machinery produces, tells us how our experiences of the
world might come about
● Machinery= Bottom-up processes
2 goals of perception- cognition and perception
Recognise an object-
● Recognising an object is to categorize
● 3 different levels
● Superordinate level - tennis ball recognised as an inanimate object
● Basic level - tennis ball recognised as a ball
● Subordinate level - tennis ball recognised as a specific token or exemplar of a
category eg tennis ball or Barneys ball.
-Being able to see sometimes means your perception will be distorted e.g brain
damage, (look at rose and cylinder slide)
-Being able to see does not mean your be able to recognise
Stages in object Recognition-
● Object recognition has 3 main stages
● Perception of features - The visual perception detects features, colours, edges
etc… there's stuff out there.
● Perception of Groups - Individual features are grouped into simple figures that
are distinct from the background of other features
● Recognition- Matching visual perception to memory, the groups of features are
matched to long term memory.
Stage 1- perception of features
● First and simplest feature
● Difference in light- luminance
● Known as luminance edge
● Dark changes to light and vise versa
● Edges are the first available features in vision, starting process of objects and
faces
, Ganglion Cells detect edges
● Detecting edges belongs to these cells in retina
● 1 million ganglion cells per retina
● Axons of these cells only output of the eye
● Their axons form the optic nerve
● Place where they leave the retina on the way to the brain is the blind spot
Mango and Ganglion Cells
● Magnocellular- Big cells receive input from many rods and cones, which means
they have large receptive field
● Parvocellular- Small cells, light and information from just a few cones, which
means they have a small receptor field
Ganglion cells Receptive Fields
● Each has a receptive field
● Area we see is our visual field
● Left is our left visual field, and right is right visual field
● Part of the visual field to which any a single neuron responds is that neurons
perspective field.
-Ganglion cells detect edges as a result of their centre-surround organisation
-On centre Ganglion cells- centre excited by stimulation of light
-Cell activity stimulated by light
Short tale of 3 nothings (on powerpoint slide 16)
How do Ganglion Cells detect edges?
● Centre-surround organizations of retinal G cells emphasize edges.
● A bunch of neurons are always at resting state, but activate somehow
● Any G cells that are far from edge show low or no activity
● At around edges either increased or decreased
● When increase or decrease is detected, cell is activated
● Activation transmitted down visual system
● All edges treated as equals
Slide 22- Off centre will react to dark text , no light
On centre will react light text, reacts light
-Visual info does not stay in the retina long
Big picture
● Looking at the machinery, the brain- tells us which bits do what and when
● Looking at what the machinery produces, tells us how our experiences of the
world might come about
● Machinery= Bottom-up processes
2 goals of perception- cognition and perception
Recognise an object-
● Recognising an object is to categorize
● 3 different levels
● Superordinate level - tennis ball recognised as an inanimate object
● Basic level - tennis ball recognised as a ball
● Subordinate level - tennis ball recognised as a specific token or exemplar of a
category eg tennis ball or Barneys ball.
-Being able to see sometimes means your perception will be distorted e.g brain
damage, (look at rose and cylinder slide)
-Being able to see does not mean your be able to recognise
Stages in object Recognition-
● Object recognition has 3 main stages
● Perception of features - The visual perception detects features, colours, edges
etc… there's stuff out there.
● Perception of Groups - Individual features are grouped into simple figures that
are distinct from the background of other features
● Recognition- Matching visual perception to memory, the groups of features are
matched to long term memory.
Stage 1- perception of features
● First and simplest feature
● Difference in light- luminance
● Known as luminance edge
● Dark changes to light and vise versa
● Edges are the first available features in vision, starting process of objects and
faces
, Ganglion Cells detect edges
● Detecting edges belongs to these cells in retina
● 1 million ganglion cells per retina
● Axons of these cells only output of the eye
● Their axons form the optic nerve
● Place where they leave the retina on the way to the brain is the blind spot
Mango and Ganglion Cells
● Magnocellular- Big cells receive input from many rods and cones, which means
they have large receptive field
● Parvocellular- Small cells, light and information from just a few cones, which
means they have a small receptor field
Ganglion cells Receptive Fields
● Each has a receptive field
● Area we see is our visual field
● Left is our left visual field, and right is right visual field
● Part of the visual field to which any a single neuron responds is that neurons
perspective field.
-Ganglion cells detect edges as a result of their centre-surround organisation
-On centre Ganglion cells- centre excited by stimulation of light
-Cell activity stimulated by light
Short tale of 3 nothings (on powerpoint slide 16)
How do Ganglion Cells detect edges?
● Centre-surround organizations of retinal G cells emphasize edges.
● A bunch of neurons are always at resting state, but activate somehow
● Any G cells that are far from edge show low or no activity
● At around edges either increased or decreased
● When increase or decrease is detected, cell is activated
● Activation transmitted down visual system
● All edges treated as equals
Slide 22- Off centre will react to dark text , no light
On centre will react light text, reacts light
-Visual info does not stay in the retina long
