PSYC 376 EXAM 2

Neural Convergence

Retina projections to the primary visual cortex: On center off surround —→ Line detector cells —→ Complex cells —→ End stop cells

Multiple presynaptic neurons converging on a postsynaptic target. More neural convergence with horizontal and vertical lines than oblique lines. Less acuity, more sensitivity.

Orientation Tuning Curve

Measuring how often a cell fires depending on its degree orientation, measured in hertz (action potentials per second)

Line Detector Cells

Result of on-center off-surround cells converging, detects lines.

Complex Cells

Result of line detector cells converging, respond to lines of particular orientation that are moving but don’t give direction.

End Stop Cells

Result of complex cells converging, give us complex shape pattern and track movement in a particular direction.

Action Pathway

Theorized to exist, there are 2 or 3 total pathways in the brain. Card swiping example, fig 4.26

Fusiform Face Area

Processes faces

Parahippocampal Place Area

Processes spatial, 3D geometric spaces and respond to location not objects.

Extradite Body Area

Responds to body stimuli or body part like shapes excluding faces.

Cortical Magnification

There is more primary visual cortex space dedicated to processing fovea information over periphery. Produces greater acuity because of less neuroconvergance, directs attention.

Retinotopic Map

An image on the retina is inverted compared to the image in the real world

Where Pathway

1. Parietal Lobe

2. Dorsal Pathway

3. Where objects are

What Pathway

1. Temporal Lobe

2. Ventral Pathway

3. What objects are

Mishkin Monkeys

1. Object discrimination

   1. Choose which object to pick up

   2. Temporal lobe area removed, can’t discriminate objects

2. Landmark discrimination

   1. 2 identical objects w/ landmark distinguishing one from the other

   2. Parietal lobe area removed, can’t find the correct object

3. Double dissociation

   1. The impairment of one pathway does not effect the other

Cat Experiment

Critical Period, changes how cats perceived lines pg 74

Viewpoint Invariance

An object is viewed as the same object even if the viewpoint of it is altered, or in other words, the sensation changes but the perception remains the same.

Example: Chair image in textbook pg 94

Gestalt

The whole is greater than the sum of the parts. (Ex. grouping, segregation)

Perceptual Organization

Process by which elements in the external world are perceptually grouped together to create the perception of an object.

Scene Completion

We complete incomplete images and/or if a stimuli is close enough to our neural representation we can fill in the gaps. (Ex. hidden objects and blurry objects)

Inverse Projection Problem

The issue of determining what object is in the real world that is projecting onto the retina.

Retinotopic Map

Locations in the cortex respond to location in the retina. Related to cortical magnification.

Pop-Out Effect

What we attend to visually always seems to be in front of the background. (Ex. face-vase)

Perceiving Scenes

1. Gist: Gaining the general contents of scene one is perceiving, happens in under a second.

   1. Can lead to false positives.

2. We always perceive light as coming from above.

3. Semantic Regularities: Schemes inform what we expect to see in a scene.

Visual Scanning

People tend to attend to very little of an image, focus on the center and faces.

Fixation & Saccadic Eye Movement

Fixation is done by the fovea and rapid, constant eye movement helps attend to a larger visual field.

Overt Attention

What the fovea is currently attending to. (Ex. Computer screen study)

Covert Attention

Shifting attention without moving ones eyes. Attending to something without fovea being oriented on it. (Ex. Computer screen study)

Opportunity Costs

?

Attentional Capture

Anything abnormal, different, or unusual captures attention. (horizontal and vertical green and red lines example)

Same Object Advantage

Grouping, gestalt??

Priming

More likely to generate one response over another

Visual Distractors

When attention is divided it significantly compromises behavior, is an opportunity cost.E

Ecological Approach (to perception)

Focuses on studying the perception of moving observers instead of focusing on studying the perception of stationary observers. Movement causes stationary objects to appear in motion due ton the relative changes of the observers movement through the environment.

Optic Flow

Provides information on direction and movement (heading information). Flow of the world the world past you.

Gradient flow provides information on movement speed, modified by learning.

Focus of Expansion

Goal location of movement.

Visual Inputs

Having a focus point helps with balance.

Swinging Rooms Study

Child on stationary floor, wall moves TOWARD child, child think they’re moving forward so they lean back and fall. Wall moves AWAY from child, child thinks they’re moving backwards, leans forward to compensate. Demonstrates how the sensory systems (visual and motor) are working against one another.

Landmarks

1. Retrosplenial cortex damage, directional ability

2. Hippocampus: maps particularly not common locations

3. Virtual Hallway Study

   1. Decision point with toy (can go multiple different directions) vs. Non-decision point with toy (only one direction option).

   2. Participants were more likely to recognize/remember toys at decision points, they found this out by measuring brain activation when shown the toys which shows a physiological approach. There was higher brain activity when shown toys from decision points.

Place Navigation

1. Rat “cross” maze

   1. Rats remembered the place and goes left instead of right when their initial position was changed (starting point A vs starting point C) (both times end at point B). this shows that they cognitively mapped the spatial layout of the maze. Navigation involves where you are and what direction you’re going.

medial superior temporal area

critical for the perception of movement

Parietal Reach Area

Associated with dorsal pathway, involved with reaching and grasping, neurons here respond differently to different types of reaching/grasping

mirror neurons

Neurons that respond not only when an action happens but also when an action is observed, used in vicarious learning.