Perception and sensory

Juno's lects

Receptors in the skin on the genitals map between the thigh and abdomen in the _______ cortex, and this form of neural mapping is known as ______.

a. motor; somatosensory

b. somatosensory; retinotopy

c. operculum; retinotopy

d. somatosensory; somatotopy

d. somatosensory; somatotopy

An accidental view of an object is where:

a. We interpret a 2D object as a 3D one by inferring the information we cannot see directly.

b. We interpret a 3D object as a 2D one because we can only see one face, which is an improbable view.

c. We interpret a 2D object as a 3D one because it is unlikely to be anything else.

d. We interpret a 3D object as a 3D one when it is partially occluded.

b. We interpret a 3D object as a 2D one because we can only see one face, which is an improbable view.

A cube is seen behind another rounder object that partially occludes it. This is best explained because:

a. It exhibits good continuation

b. It generates T-junctions at a common edge in the image

c. It has a different colour

d. It has straight edges, and these edges are in plain view

b. It generates T-junctions at a common edge in the image

Simple cells in V1 (the primary visual cortex) respond best to:

a. Small spots of light presented to the visual field

b. Small or large spots of light varying in colour contrast

c. Edges or contours in an image 

d. Dark spots in an image that fall in the excitatory part of their receptive field

c. Edges or contours in an image

Area MT is:

a. found in the dorsal extra-striate visual pathway

b. part of the LGN

c. found in V1

d. found in the extra-striate ‘what’ pathway

a. found in the dorsal extra-striate visual pathway

Why is perception a hard problem?

This is because our brain gives us an estimate of what we are looking at where our brain is constantly solving the inverse problem of viewing 2D images to 3D images.

What can we learn about the brain from illusions?

• Illusions indicate we don’t know exactly how things are structured in the world around us

• They provide insight into how perceptual systems break down

What is segmentation and grouping?

Our brain can select key features to recover complex information about objects (eg.faces). Although, single features are not usually enough to recognise a face or determine whether a smile is genuine

Name Gestalt’s grouping laws and describe them (6 laws)

What evidence is there for high level information influencing the processing of low-level sensory information?

Bugelski demonstrated how the “rattish man figure” is disambiguated by high level information.

what is accommodation and what are its types? (note that light reflected by surfaces is captured onto the sensory tissue at the back of the eye/retina)

Accommodation is the changing of the shape of the lens to adjust our focus of objects at different distances

far accommodation: the lens becomes flatter to where the far image is focused and near image is blurred

near accommodation: the lens becomes rounder to focus light from a near object where the far image is blurred and the near image is focused

The optic nerve has a blind spot.

True or False

True. There are no photoreceptors in the optic nerve

How is colour coded in the retina and brain?

They are coded through rods(scotopic/night vision) and cones(photopic/daylight vision) which contains visual pigments. Each cone is sensitive to different parts of the light spectrum.

Ganglion cells relay the integrated information to the brain out through the optic nerve.

Note:There are no rods in fovea and only cones.

What is the fovea?

The fovea is next to the blind spot and it receives images of what you are looking at

What are the opponent processes

What are the general visual pathways for perceiving colour, form, and motion?

The LGN (Lateral geniculate nucleus) receives information from ganglion cells and integrates information from the eye concerning colour, form, and motion.

Visual information is then projected to the primary visual cortex —> some projections may go directly to MT (medial temporal)

What is retinotopy?

the organisation of visual information from the retina to the brain. It's also known as retinal mapping.

What are the dorsal/ventral pathways?

Dorsal (where): MT

Ventral (what—> descending): V1, V2/V3, V4

What is V1?

V1 is your primary visual cortex which responds to 2D lines (contours and edges)

What is V2/V3

They are the extra striate visual cortex which integrates signals from V1 to form more complex information.

• groups lines into complex contours and 2D shapes

What is V4?

V4 is responsible for perceiving colour where colour constancy depicts how colour is perceived invariable across changed in illumination

What is MT/V5?

MT, located in the dorsal pathway, receives input from V1 and the LGn which perceives retinal motion (moving objects)

What are receptive fields?

How does damage to specific cortical regions affect perception?

V1: results in blindness

V5: Blindsight where some blind people can move around in the world while avoiding objects, but have no conscious visual awareness of objects in the scene.

1. Receptors in the skin on the genitals map between the thigh and abdomen in the __________________ cortex, and this form of neural mapping is known as _____________.

   a. somatosensory; retinotopy

   b. somatosensory; somatotopy

   c. operculum; retinotopy

   d. motor; somatosensory

b. somatosensory; somatotopy

When we rotate our head to the side, we make compensatory eye movements to maintain stable gaze. These eye movements are primarily driven by:

a. Semicircular canal (SCC) signals

b. Somatosensory signals from neck muscles

c. Vection signals

d. Otolith signals

a. Semicircular canal (SCC) signals

The ___________ resolution of hearing is better than for vision, but the ___________ resolution of vision is better than for hearing. They work together to improve perception through a process known as ____________.

a. spatial; temporal; grouping

b. spatial; temporal; multisensory integration

c. temporal; spatial; multisensory integration

d. temporal; spatial; grouping

b. spatial; temporal; multisensory integration

Our ability to recognise the difference between male and female voices singing the same note depends on the perception of ______________, which is the perception of _________________:

a. purity; timbre

b. pitch; frequency

c. timbre; purity

d. frequency; pitch

c. timbre; purity

What are the concepts of spatial frequency and visual acuity?

Spatial frequency: The rate of change in luminance across a finite region of an image quantified in cycles per degree. eg.your thumb outstretched is about one degree visual angle

Visual acuity: the ability to resolve fine details in an image which is greates in the fovea and lower in periphery

What are the different types of eye movements

Saccades: As objects move around rapidly, we use saccades to capture new images onto our fovea. (used when reading)

Smooth pursuit: As objects move around the scene, we maintain the capture of their images on the fovea using slow eye movements.

What is the basic anatomy of the vestibular system

• The vestibular system consists of the outer ear, middle ear, and inner ear (containing labyrinth) which helps with the control of gaze and posture

  • Encased in bone so the sense organs move with the head

• The inner ear contains sensory structures with receptor cells that detect gravitational forces, including angular and linear head accelerations in space

THE LABYRINTH

What is the physiology of the vestibular system

The hair cell receptors in the semicircular canals (SCCs) and otoliths generates action potentials (APs) which code for head acceleration in two different directions. (The bending of hair-cell receptors can either excite the neuron or inhibit it)

note: otoliths also sense gravity

Define somatosensation, proprioception, haptic perception

Somatosensation: the sense of touch 

Proprioception: the ability to sense changes in the position and orientation of the body and its parts (eg. limbs and joints)

Haptic perception: The perception of an object’s shape, size, and identity on the basis of touch and proprioception

what is the importance of multisensory integration?

Although somatosensation primarily helps us regulate our behaviour in response to dynamic events (eg. adjusting grip and avoiding painful stimuli), our visual, vestibular, and somatosensory systems work together to allow us to perceives and interact with objects.

What are the different properties of sound waves and how do they affect perception?

Amplitude: gives rise to the percept of loudness

Frequency: Gives rise to the percept of pitch

Purity: gives rise to the percept of timbre (or ‘colour’)

instruments all generate the same component frequencies when played at a given pitch. The pitch of an instrument is mainly conveyed by the fundamental (lowest) frequency, and timbre by the relative amplitudes of overtones.

Overtones: are whole number ratios of the fundamental frequency

How are sounds converted from sound waves through the atmosphere into neural representations?

The middle ear transmits the eardrum’s vibrations to the oval window, which transmits them through the fluid filled cochlea.

How are sounds converted from sound waves through the atmosphere into neural representations?

The middle ear transmits the eardrum’s vibrations to the oval window, which transmits them through the fluid-filled cochlea.

What is tonotopy

the spatial arrangement of where sounds of different frequency are processed in the brain

How can we localise sound sources in our environment?

Interaural time difference (ITD): used for local frequency sounds

Interaural intensity difference (IID): useful for localising high frequency sounds

What are some of the ways that multisensory integration can help resolve auditory ambiguities

• The auditory system has low spatial acuity compared with the much higher spatial acuity in human vision.

  • We can use the high spatial acuity of vision and high temporal acuity of hearing through multisensory integration.

eg. McGurk effect