The phrase ‘short-term memory’ has entered our everyday language and is often used to mean something rather different than the psychologists’ definition. Casually, the term is used to refer to the relatively recent past, such as something that happened earlier in the same day or the previous day. In fact, the contents of short-term memory memory could not exceed over this lengthy time, and usually last for no more than a few seconds. The type of memory to which this everyday use of short-term memory refers is what psychologists call ‘episodic memory’.
Short-term memory is the ability to hold information in your mind for a few seconds. According to the research, information can be held in short-term memory for about 7 seconds. Short-term memory can be thought of as the use it or lose it memory. When new information requires a person’s short-term memory, the previous information held is either stored or discarded. Repeating information is one way of extending the interval, however, information not acted upon will be lost from short-term memory within 15 to 20 seconds. The other limitation of short-term memory is the number of units (referred to as span) that can be held at a time. In a typical individual the span is about 7 units (plus or minus 2). What changes developmentally is the size of the units. For example, for a beginning reader each phoneme (sound) is a unit, later, words become the units, and finally, ideas become the units.
The amount of information that can be held in short term memory is limited and if the limit is exceeded, we will forget at least some of what we are trying to remember. For example, multiplying 232 and 561 in our heads is not possible for most of us because it would require the storage of more information than the limited capacity of Short Term Memory can hold. Remembering a telephone number or remembering a list of words is a good example of an activity that relies on short-term memory.
Within a particular age group, there is a variation in short-term memory capacity between individuals. For example, in a classroom of seven year olds, some students will have the short-term memory capacity of the average five year old while others of an average eleven year old. Short-term memory capacity is associated with academic achievement in key areas of the curriculum from the earliest point at which children enter school through adolescence. Memory functioning is the foundation of all cognitive processing and learning.
Students with limited memory functions may (1) appear inattentive; (2) have difficulty following directions or recalling sequences; (3) have trouble memorizing factual information; (4) have difficulty following a lecture or a class discussion; (5) have trouble taking notes; or (6) struggle to comprehend what has been read or sated.
Different kinds of memories:
Working memory = subset of short-term memory system. The ability to manipulate information for short periods of time. For example, following lengthy directions to reach a destination.
Episodic memory = long-term memory system. Remembering information from the relatively recent past, spanning minutes through days (remembering what you had for lunch today).
Autobiographical memory = long-term memory system. Memory for significant events across the lifetime (remembering your wedding day).
Semantic memory = long-term memory system. Supports knowledge such as facts, and word meanings (knowing that Paris is the capitol of France).
Procedural memory = long-term memory system. Memory for skills such as driving a car that have been acquired through repeated practice and can be executed automatically without mental effort (riding a bicycle).