Chapter 5- STM and working memory Flashcards
Memory
The process involved in retaining, retrieving, and using information about stimuli, images, events, ideas, and skills after the original information is no longer present. Your memory is activated whenever a past event affects the way you think or behave.
Sensory memory
When your perception continues for a fraction of a second after the presentation of a stimulus (briefly retains sensory stimuli). This is what makes it possible to perceive movies, and what is active when something is briefly illuminated, like when a face is illuminated by a flash of light.
Short term/working memory
Information that stays in our memory for brief periods (10-15 seconds). Anything longer than this is long term memory!
We can make the information persist by rehearsing it, like when you repeat a phone number to yourself until you can write it down.
Long term memory
Stores information for longer periods of time, from minutes to many years. Includes episodic, semantic, and procedural memory.
Types of LTM (3)
- Episodic memory is the memory for experiences
- Procedural memory is the memory for tasks that involve muscle coordination, like riding a bike.
- Semantic memory- memory for facts, or for the names of objects
The modal model of memory (Atkinson and Shiffrin, 1968)
This model proposed 3 types of memory:
1. Sensory memory- initial stage that holds all incoming information for seconds or fractions of seconds.
2. Short term memory- can hold 5-7 items for 15-20 seconds
3. Long term memory- can hold a large amount of information for years or decades.
Control processes
Atkinson and Shiffrin also proposed control processes- dynamic processes associated with the structural features that can be controlled by the person and can differ from one task to another.
Rehearsal
Repeating a stimulus over and over, like repeating a phone number so you can remember it. Eventually, the number can be stored in LTM and then recalled to STM as you remember it. This is an example of a control process- in order for the number to enter STM, all information that enters the eyes enters sensory memory. The person must also use selective attention to focus on the information they want to store in STM.
Encoding
The process of storing information in LTM. Retrieval is the process of remembering information stored in LTM.
Persistence of vision
The continued perception of a visual stimulus even after it’s no longer present. It only lasts for a fraction of a second, so it’s not obvious when a stimulus is presented for a long period of time.
However, with brief stimuli, it’s more noticeable.
How is a sparkler’s trail an example of persistence of vision?
When a sparkler is moved through the air, it appears to create a trail of light. There isn’t an actual trail, your mind just creates a perception of it.
How is a projector’s shutter an example of persistence of vision?
A single film frame is put in front of a projector lens, the projector’s shutter opens and closes, and the image on the film frame flashes onto the screen. When the shutter closes, the screen is actually dark before it moves on to the next frame. This occurs many times per second, and we do not perceive the darkness in between frames due to persistence of vision.
Sperling’s experiment
Measuring the capacity and duration of the sensory store. Sperling wanted to determine how much information people can take in from stimuli. Used partial report, whole report, and delayed partial report methods
Whole report method
Sperling flashed a series of letters on a screen very briefly (for much less than a second) and asked participants to report as many letters as possible.
This part of the experiment is called the whole report method- participants were asked to report as many letters as possible, and could recall 4.5 out of the 12 letters.
Partial report method
To prevent “fading” of the stimulus, participants were asked to report the letters in a single 4 letter row. After the letters had disappeared, a tone sounded to indicate which row to report- the letters were no longer visible, but participants could direct their attention to the trace of the letters in their mind. They could report 3.3 of the 4 letters.
Delayed partial report method
The letters were flashed on and off and the cue tone was presented after a short delay. Participants were only able to report about 1 letter in the row. This decrease in performance is due to decay of iconic memory
Iconic memory
Brief sensory memory for visual stimuli- corresponds to the sensory memory stage of the modal model.
Echoic memory
The persistence of sound, and lasts for a few seconds after the stimulus is presented, like sensory memory for auditory stimuli. This is like when you say “what?” after a person says something, but then you hear what they said in your mind.
Recall
Participants are presented with stimuli and asked to report the stimuli back after a brief delay
What is the duration of short term memory?
Participants will forget information, such as a sequence of numbers, within 15-20 seconds if they do not rehearse the information.
Digit span
The number of digits a person can remember, one way of measuring STM capacity.
The average capacity is 5-9 items- this was suggested by George Miller (1956). STM capacity can be described as a bottleneck
Change detection
STM capacity has been set at 4 items from more recent research (Luck and Vogel, 1997). Two displays are flashed briefly, one after the other, for less than a second. Participants were asked to indicate whether the two displays were the same or different. The task is easier if the number of items in the displays is within the limit of STM. Performance began decreasing when there were 4 or more squares in the displays.
Chunking
Miller (1956) describes chunking as the fact that small units (like words) can be combined into larger meaningful units (like phrases, sentences, or paragraphs). A random series of 8 words, for example, is much easier to remember if they can be rearranged into meaningful phrases or even into a sentence. Chunking can increase the memory span to 20 words or more, and it allows the STM to deal with daily tasks, like chunking letters into words during reading.
Chunk
A collection of elements that are strongly associated with one another but are weakly associated with elements in other chunks. Chunks are defined by prior knowledge. “Zoo” is more meaningful when grouped with “city” but not when grouped with “child”.