Contemporary cognitive models point to several types of memory:
1. Sensory memory
2. Short-term memory
3. Working memory
4. Long-term memory
Sensory Memory
Information from outside world enters the cognitive system through sensory memory, a kind of information scratch pad to record information from the senses. Each input channel has a secondary memory.
Information is held in the secondary memory for a very short time, with fast access and fast decay.
If the presentation of an interaction changes faster than the decay rate, the information from interaction will be lost.
Sensory memory also has extremely limited capacity.
There is some processing of sensory data , even in brief time the information resides there. The information in secondary memory is filtered by attention and passed to short-term memory.
Short term memory
Information from the outside world enters the cognitive system into short-term memory via perception.
Information from sensory memory is interpreted by the perceptual system and moved to STM.
STM has limited capacity, fast access, and fast decay, although not as fast as sensory memory. Distractions make it even more difficult for STM to hold information.
Working Memory
WM supports the short-term storage of information that was depicted previously with STM. Additionally, WM includes greater emphasis on information-processing capabilities than traditional STM model.
The key function of WM is to provide a place for formation of mental models.
WM consist of two scratch pads:
1. One scratch pad is for visual information
2. other scratch pad is for auditory information
Application to HCI :
A number of researches have found that multimedia presentations that are "dual", meaning that the information is conveyed both in auditory and in picture form, are more effective than single presentations for variety of task, especially learning tasks.
Because the sketchpads in WM have limited capacity, multimedia presentations that use both types of information representations are more likely to be effective than those that are strictly visual or those that are delivered strictly by auditory methods.
Long-Term Memory
Long term memory may be permanent memory. It is an open question whether people ever truly forget information that is stored in LTM. LTM has essentially infinite capacity and it has slower access as compared to STM.
Information gets into LTM from STM via rehersal. That is why with practice you tend to recall everything better.
Getting information from LTM can happen in two ways:
Recall and Recognition
In recall, information to be retrieved from LTM must first be found and then recalled.
In recognition, an information cue is provided and information retrieved is matched against the presented cue.
Application to HCI:
Generally, recall is more difficult process than recognition. So we can infer that menus are better for novices than command line. With menus, all options are presented explicitly, so selecting a menu option involves recognition.
Using command line involves recall.
A bit of Philosophy:
These are some concepts of philosophy but they also hold true for psychology.
Declarative Knowledge:
Declarative knowledge is knowledge of facts. These are "know-what" about things. Here is an example of declarative knowledge " What is the capital of United States of America?". The answer to this question is an example of declarative knowledge.
Procedural Knowledge is "know-how" about things. Procedural knowledge is "how" you process about doing a certain thing. These are more subtle to communicate.
Representation of Knowledge:
Knowledge is organized hierarchically, temporally, and in networks. Both information and its organization change over time.
Experts develop complex, multilevel bodies of knowledge in their domain or expertise. This knowledge is stored in LTM. Some knowledge is semantic, or about meaning of things.
Semantic knowledge is knowledge of general concepts and is independent of specific situations.
For example, an expert programmer understands the concept of array regardless of the programming language.
Some knowledge is about surface structure and is called syntactic knowledge. Syntactic knowledge is also stored in LTM, but it is more detailed than semantic knowledge and less structured cognitively.
Syntactic knowledge is acquired by rote and more easily forgotten than semantic knowledge.
Application to HCI:
1) Syntactic knowledge is acquired by rote and is more easily forgotten than semantic knowledge. There are some "occasional" users who use the systems for once in a while. These users may more easily remember the semantic details of the task than the syntactic details of the interface's operations. Designers should provide cuing when possible for operation and syntactic details of an interface use.
Active Learning
Active learning is a concept taught is education classes. It is also a concept in cognitive psychology. Active learning says that people learn better if they are engaged in learning actively.
Application to HCI:
Users may learn more effectively in environments where they have to develop explanations for themselves. So, active learning is promoted when a user is placed in problem-solving situations that allow them to connect prior knowledge to current situation.
References:
Usability Engineering process, products and examples by Laura Leventhal and Julie Barnes
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