Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
10 Cards in this Set
- Front
- Back
|
What is the constructivist theory of perception? Name 2 psychologists who support this? What do they state happens when we look at something? What happens on rare occasions? What is the issue with this? Name 1 piece of evidence for the constructivist theory? 2nd piece of evidence? |
States we rely on top-down processing and that perception is the end product of external stimulation and internal hypothesis which we interpret using the information we receive, our expectations and knowledge. Gregory and Helmholtz. We develop a perceptual hypothesis based on prior knowledge and previous experience. Hypotheses are incorrect and so we are prone to error e.g. the Muller-Lyer illusion. Most experimental demonstrations are based on artificial stimuli which has a very top-down processing nature. Unambiguous or unlikely objects often get mistaken for likely objects e.g. Hollow mask illusion (nose does not point inwards). Perceptions can be ambiguous e.g.Necker cube which flips between two orientations as the brain formulates two plausible hypotheses and cannot decide between them. |
|
|
Who argued against this theory? What did they say perception was instead? What did he argue was important in the study of perception? What did he call this? What else did he argue was important? What did he argue was wrong with lab situations? What did he emphasise the importance of? What did his theory rely on? What are they? |
Gibson. Bottom-up process and saw it as the direct pick-up of information. Has to be ecologically valid and never considered in isolation from the background texture. Ground theory approach.. Background. Visual stimuli without this direct information people must make inferences. Motion in the environment, both in the observer and object. 3 important components. 1. Optic flow patterns. 2. Invariant features. 3. Affordances. |
|
|
What is optic flow? What does outflow from a visual target denote? What does inflow to a visual target denote? What does flow altogether denote? What specifies a turn? |
Pattern of apparent motion of objects, surfaces and edges in a visual scene caused by the relative motion between an observer and a scene. Approach to the target. Retreat from the target. Movement (non-flow=static). A shift in the centre of outflow. |
|
|
What is invariant features? What are affordances? What is motion parallax? Name 1 reason optic flow is important? Name a lab experiment that demonstrates this? What happens in this experiment? What does it demonstrate? |
We rarely see a static viewpoint of things, textures expand when you approach objects and contract when you move away. Because the flow of texture is invariant and the pattern structure is available, it provides a source of information about the environment and depth cues. They are cues in the environment that a perception such as brightness (brighter objects are perceived as closer), relative size and optic array. The notion that objects that are closer appear to be moving faster and distant objects appear to move more slowly because of the changes in angle on the retina as we move. The angle of near objects changes faster than those that are further away. Balance and posture. Lee's swinging room. Moving the room forward creates the optic flow pattern that will result if you swayed backwards. As a result, participants will lean forward to compensate despite the floor being stationary. How visual information can override information obtained from our mechanical or vestibular system. |
|
|
What else is optic flow important for (3 things)? What must we do to carry out these activities? What is the formula? What is another way of carrying out these activities? What happens as you approach an object? What effect does this have on our pupils? When can the time-to-contact ratio be calculated without having to estimate distance and speed? |
1. Catching balls. 2. Avoiding collisions. 3. Determining time-to-contact. Estimate speed. Time= speed/distance. Lee's rate of dilation flow field. Gets bigger. Get smaller/contract (concentrating also make pupils contract). When movement of the object is at a constant velocity and using the inverse rate of dilation. |
|
|
What does this not specify? What does it specify? What is the formula for Lee's rate of dilation? Where does evidence for this method come from? |
The distance of a surface. The time until we contact it. Time-to-contact=1/rate of dilation. Long jumpers; if they are filmed during a run-up the correction phase of the run-up uses the rate of dilation of the board in their view. |
|
|
What is the perception of movement crucial for? What does this explain? What have animals learnt to do? What is the most straightforward way to create the perception of movement? What is this called? What happens when detecting visual motion of something that is large? What does this require the need for? |
Survival in animals. Why animals can lack depth and colour perception but none lack the ability to perceive motion. Remain totally still when they sense danger as remaining still may mean they have a chance to be unseen. Move an object across an observer's field of view so that it changes position/angle on the retina. Real movement because the object is physically moving. Will activate both receptive fields causing the same firing rate. A delay component and a comparative component which allows directional computation of movement. |
|
|
What is the directional computation of movement known to be? Why? What is apparent motion? How do we detect movement in movies? What is the correspondence problem? |
Velocity sensitive. Does not fire optimally if outputs from different receptive fields are out of sync. Where an optical illusion of motion is produced by viewing a rapid succession of still pictures of a moving object (used in movies and tv). The visual system must determine which features in a visual scene should be matched over time. This is known as correspondence. Ascertaining which parts of an image correspond to which parts of another image and where differences are due to movement of the camera, the lapse of time and the movement of objects in photos. |
|
|
What must the visual system take into account? How must it do this? What does comparing these 2 signals allow? What is saccadic suppression? |
Movement of eyes as if our movements were to follow something such as a moving bird. It doesn't change position on the retina. The area of the brain (superior colliculus) that controls the movement of eyes must send a signal (corollary discharge) to the area that detects movement on the retina. The visual system to determine whether an image has moved or not. The phenomenon in visual perception where the brain selectively blocks visual processing during eye movements in a way that stops motion blur and there being a noticeable difference/gap in visual perception (the shutdown occurs for the duration of a saccade). |
|
|
What are cells that respond to direction known as? Where are they found? Where are they never found? What happens when you stimulate neurons in V5? What does this suggest? What happens as a result of lesions in V5? How is movement seen? What can affect our ability to detect motion? How? What must area MST have? |
Direction-selective. MT/V5. V4. Increases behavioural sensitivity to a particular direction of motion. Our perception of movement is based on the activity of neurons in V5. Disrupt the perception of motion. This is called akinetopsia. In a series of freeze frames. Context. In a blank field, we can detect motion when its displacement is greater than 0.2 degrees per second but if the field contains vertical lines, we are able to detect movement as small as 0.02 degrees per second. Cells which respond to more complicated aspects of motion such as expansion and rotation and these signals may also be involved in optic flow. |
