Memory

Memory Capacity

The immediate memory capacity of a human is rather limited, as the number of stored objects is 7±2. These objects being numbers, words, or images. So we can say that working memory deals in chunks, and varies depending on the complexity. For example, longer or unfamiliar words will lower the memory capacity.

Auditory Memory

The phonological loop is linear, single-channel, and has a very limited storage duration - approximately two seconds. Information stored there can be rehearsed but that captures the "inner monologue" and interferes with speech production. There is some evidence that drivers encode information about cars behind them using declarative statements in auditory memory.

Visuo-spatial Memory

Humans evolved to store spatial information in order to avoid obstacles and navigate a largely planar world. Spatial memory is extremely powerful, as you can recall dinner guests by mentally stepping around a table. Some people can recall the precise order of a full 52-card deck by using the Method of Loci (i.e., the Memory Palace).

Long-Term Memory

Not a faithful representation of stimuli, objects, or events - as what details get encoded depends on what is being attended to. When memories are retrieved, lots of details are filled in from expectations and previous experience. Every time a memory is retrieved, certain feature are reinforced while others decay. So when you recall a past memory, you're more like "recalling the last time you recalled it."

Memory Activation

There are three factors that are involved here:

• Practice: your name has a high activation because you've had to recall it thousands of times
• Recency: recently recalled or encoded memories are "fresher" - making them more easily accessible
• Context: nodes that were encoded at the same time or are related get connected in memory

Recognition vs. Recall

Recognition involves merely confirming that a memory node is the one you meant to access. In contrast, to recall is the process of remembering without any additional cues or context.

Recall-based interfaces such as command lines are taxing to the user because they require a hard memory search for both commands (e.g., mkdir) and data (e.g., ./directory/filename.ext). Recognition is easier than recall because some of the activations of related concepts have been raised before you were asked to make decisions.

Implications

• Put all items on the screen and let the user recognize the ones they want
• Use menus and buttons to indicate what the user can do in any given situation
• Use icons the user is familiar with that reference known metaphors
• Do not expect the user to remember complex sequences of steps
• Prime the user with past memories
• Enable the user to employ their own context-aiding strategies