Lecture 12 Flashcards
Define sensory memory
An internal store that holds information about the environment until we actively perceive it. It’s the first memory store before short term and long term stores.
Briefly discuss sensation, perception and cognition
It’s artificial to separate these three processes as they overlap, however, it’s helpful to do so when learning about the processes.
Discuss visual sensory memory
The sensory information is held in sensory registers. Sperling found evidence for this; he called the visual memory iconic memory. The participants looked at a fixation point and then a grid of letters were shown to them for half a second. This shows how big the visual span is for sensory memory allowing us to see how much of the world we encode. Participants remembered about 4/12 letters, showing not all information is stored in sensory memory. If only one row is cued with a tone then the participants remembered 3/4 letters. This shows that almost all information is stored but only for a short period of time, the same was found with auditory SM. An example of sensory memory is seeing words when writing with a sparkler. In order to remember sensory info, we need to attend to it quickly.
Discuss perceptual thresholds
We might register stimuli in an all or nothing fashion or it could be a continuous curve that is determined by subjective factors like mood or mind state. Research supports the continuous curve idea. For example, you retain more sensory information when actively seeking it rather than being passive. The signal detection theory explores this: a light is either shined or not in a dark room and the participants have to decide whether it was shone or not. 4 outcomes: hit, miss, false alarm, correct rejection. This grid is also used to explore forensics like eyewitness testimony.
Where does perception occur?
It’s hard to understand because models suggest that smaller and smaller areas interpret it and get more specific but then were does the perception begin. This picture theory also doesn’t make sense because it implies that perception is a literal copy of the world and that perception relies purely on incoming information. However, incoming information is sometimes structured an requires less interpretation and we bring our own interpretation to what we perceive.
What did JJ Gibson argue?
They argue that perception isn’t just interpreting a stream of light rays, it’s more active than this. It’s more about the structure of light. Gibson aimed to improve pilots’ ability to land planes by selecting those with better depth perception or by training depth perception. However, this was unsuccessful because it wasn’t just a personal thing, it also depended on how rich the environment was. So the structure of light/optic array is equally important as individual perception. From this, Gibsonian speed controls were added on roads (strips that get closer together) as it changes the structure of the perceived world. Different forms of light structure are named perceptual invariants.
Discuss the different forms of light structure
Texture gradients: knowing something is closer to you if it’s bigger.
Horizontal ratios: we can tell if objects getting further away are the same size or not by seeing at what point they meet the horizon. If they meet it at the same point, they are the same size.
Define perceptual invariants
Unchanging aspects of the environment from the observer’s viewpoint. However, motion results in the flow of this optic information.
Discuss Gestalt principles
It’s the idea that we see the world as a whole rather than breaking it into chunks. This contrasts previous ideas (Gibson) which where reductionist, they believed that we see the world in a number of separate sensations and associate them together to perceive objects. However, this doesn’t work because we often perceive an object as similar even when it consists of different parts. For example, closure can occur, like when three pacman like shapes are presented at the points of an invisible triangle, you see the triangle. Another example of a Gestalt principle, if when a face is made up of different fruits. We perceive things as a whole first and then as separate parts.
Discuss the bottom up/data driven idea of processing
It believes that it begins with stimuli, then processing and then perception.
Discuss an issue with Gibson and Gestalt’s viewpoints
It doesn’t account for how different animals perceive things differently because if we perceive all information then we should be able to see what they see. For example, red sticklebacks attack things with a red underside and it doesn’t matter if they look life like. Also, frogs can only detect static and moving edges and changes in brightness as well as moving objects. Therefore, we need to look at a top down viewpoint.
Discuss the top down/concept driven idea of processing
Stimuli input and knowledge (culture, stereotypes, education, beliefs etc.) work together to produce perception. This explains why we see faces in things that aren’t faces, like on a wall etc. This can cause our perceptions to be faulty due to our input of knowledge, allowing illusions to occur.
Discuss the Muller Lyer illusion
Two lines that are the same length look like different lengths because of the way the arrows face at the top and bottom. We can see this in the corner of rooms. Also, the leotard that goes above your waist makes your legs look longer (the muller lyer suit). Illusions are therefore highly context dependent. Some cultures aren’t affected by this illusion, perhaps because they don’t see numerous corners and edges daily.
Discuss the ponzo illusion
Equal length lines on a traintrack. The lines presented further down the traintrack look longer. If you change the context, the lines look the same length. Some illusions for example only work from a specific viewpoint.
