Visual Processing

Located in the fovea, 6 million

Bright light, colors, low sensitivity

High resolution

Cones

Located in the periphery, 120 million

Low, light, black and white, high sensitivity

Low resolution

Rods

primary area for sharp and detailed vision

Provides most detailed visual acuity

Fovea

Natural gap in vision that occurs bc the spot has no photoreceptors to perceive light

but the brain fills in the missing info based on surrounding details

blind spot

Sends visual info from the eye to the brain

Optic Nerve

Many photoreceptors converge onto a single ganglion cell, leading to a larger receptive field and less precise spatial information

6 cones to 1 ganglion cell = high resolution

120 rods to 1 ganglion cell = low resolution

How do connections between photoreceptors and ganglion cells determine the acuity of the fovea and the periphery of the retina

A portion of the sensory surface for which stimulation influences a neurons activity. With a ganglion cell depending on what is being seen the ganglion cell will fire either on center off surround or doughnut shaped.

Receptive fields are organized in a certain way because of the way ganglions get info from the photoreceptors and how they get input via a wiring connection.

What a receptive field is and how does it affect ganglion cells

Ganglion cells in the retina have center-surround receptive fields, meaning they respond to light in a specific way: ON-center cells are activated when light hits the center and inhibited when it hits the surround, while Off-center cells do the opposite. This organization enhances contrast and edge detection, which is crucial for perceptual processes like object recognition and spatial awareness in cognitive psychology.

Receptive field of ganglion cells: how are they on/off center/ surround

eye - retina- LGN- V1

ride side = left brain and

left side = right brain

Path of information flow between eyes and primary visual cortex

A line with a particular orientation

located at a particular point in the visual field

information that simple cells code is determined by wiring connections to ganglion cell output

Receptive field of simple cells

Receptive fields progress from small, simple fields in the retina (Ganglion cells) to larger more complex fields in the visual cortex. as info moves from the retina to the LGN then to V1.

Hierarchy of receptive fields

Information processing in the eye and cortex is determined by layered structural connections, where photoreceptors in the retina pass signals through bipolar and ganglion cells, which refine contrast before sending input to the lateral geniculate nucleus (LGN) and then the primary visual cortex (V1). In V1, neurons are organized into layers and columns, where signals are processed for features like edges and motion before being sent to higher visual areas (V2, V4, IT, MT) along the ventral ("what") and dorsal ("where/how") streams for object recognition and spatial processing.

How information processing in the eye and the cortex is determined by the structural connections between layers/ groups of cells at each stage?

In the primary visual cortex (V1), neurons respond to specific orientations and motion, and as signals progress to higher areas (V2, V4, IT, MT), increasingly complex features like shapes, textures, and object identities are extracted.

How early visual processes extract increasingly more complex features from visual stimuli

From features to objects

Lines and Objects

Objects of particular size/orientation/ position

Objects with position / orientation invariance

Combination of features to activate representations of more complex objects

Simple features of an object. Ex Macaroni shape to handle is macaroni shape.

Geons

You have to recognize geons to recognize an object

Evidence that geons as intermediate stage between simple features and objects

Geons are placed together to make an object

Objhect Recognition: Features to Geons

Each geon represents a object and is placed with another geon to make an object. Ex Geons set up to make a dog

Object Recognition: Relations between geons

Object is overall centered and the viewer is centered

Reference Frame

Depending on the way an item is rotated mental recognition can take a while. Some shapes were the same but different positions and some were different.

You can recognize novel orientation and shapes from either the object moving or you moving.

Mental task rotation and results, what they suggest about our object representations

Preferred views refer to the idea that we recognize objects more easily and accurately from certain angles rather than others. This suggests that our object representations are viewpoint-dependent to some extent, meaning we store mental representations that favor familiar or typical perspectives. However, with experience, we can develop viewpoint-invariant recognition, allowing us to identify objects from multiple angles by integrating different views into a more flexible representation.

Preferred views, what they suggest about our object representations

The ability to recognize novel objects and from unfamiliar orientations suggests that our object representations are not solely fixed to specific views or orientations but are flexible and adaptable. This implies that our brain constructs abstract, generalized representations of objects, allowing us to recognize them regardless of changes in perspective, highlighting the role of viewpoint-invariant recognition processes in object identification.

4o mini

novel objects and orientations, what they suggest about our object representations

Visual agnosia

Optic Ataxia

disorders indicating that different aspects of visual processing are separable

Humans are worst at upside down faces, versus other objects (Yin 1969)

• Features in correct orientation make a big difference

• Inversion effect/ Thatcher effect

• Removing or changing one feature ultimatly makes recognition challenging

• Masks also make it very difficult to recognize

behavioral and neuroscience evidence about whether faces are special:
upside-down/right-side-up faces, faces missing a single feature, cells in fusiform gyrus

Holistic processing refers to the cognitive ability to perceive an object or face as a whole rather than as a collection of individual parts. This type of processing is particularly important in face recognition, where we tend to recognize faces by their overall configuration and relationships between facial features rather than focusing on individual features like eyes or nose in isolation.

Holistic Processing

Newborns respond best to faces: real and schematic

babies are born knowing what human faces look like in all their detail

They then look at them preferentially

Newborn response to faces

Having a lot of experience with faces will ultimately help you recognize faces better

Babies are exposed to their parents face constantly making it easier for them to memorize features making it they recognize them always.

Expertise Hypothesis

Not specific to faces exactly, but can be many things

Cassia et. al (2004) found that newborns might have a top heavy patterns bias of recognizing faces.

Non specific preference to hypothesis