Memory Types, Capacity, and Cognitive Psychology Explained

Introduction

Memory is what drives our everyday life, makes us relate to or recollect things from the past, and in many ways defines our behavior. We take it for granted, as the effort required to put it to work is not yet fully understood, and that does not affect its working. It is only when we forget something that its prominence is recognized. Cognitive psychology revolves around memory. It is the branch that deals with human behavior and its relation to mental processes. The main types of memory categories are sensory memory, working memory, and long-term memory (Saxton, 2014).

Sensory memory can be attributed to the five senses we are endowed with. They send stimuli to our brains that we experience for a very short time. It is almost a gift that this part of memory has the capacity to forget stimuli soon enough. In the absence of that capacity, we would be overwhelmed by the multitude of signals that our sensory organs continuously send to the brain.

Working memory is the part that processes information coming to us by way of stimuli. It processes only that information to which we pay attention. The amount of information that working memory can process and retain is very limited. This can be understood from the fact that we can retain only the number of words spoken in approximately two seconds. Slow talkers will utter fewer words in those two seconds than faster talkers, meaning the working memory can cope with less content from slower speech. Another way of understanding working memory is to consider what happens when memorizing a phone number (Saxton, 2014).

The Nature of Retrieval Organization

Cognitive theories have established that, in order to achieve better and longer recall, information is broken down into smaller, interrelated pieces that can also be associated with objects sharing similar connotations. Each individual may have his or her own method of clustering memory. This process — in which chunks of information are processed by establishing their relationship to some concept or idea already stored — is known as subjective organization (Gates, 1917; Tulving, 1962). The basic idea is to ease storage and thereby facilitate retrieval over a longer period of time.

Shared memory has been studied in the context of the connection between individual and group memory, and retrieval organization has been found to play a major role in shared memory.

The duration for which the brain can store information is fully dependent on how well it has been organized (Mulligan, 2005; Puff, 1979; Zaromb & Roediger, 2010; see also Congleton & Rajaram, 2012; Luhmann, Congleton, Zhou, & Rajaram, 2014). It has been established that it is easier to retrieve information that has been chunked than information that has not been clustered (Miller, 1956; Zaromb & Roediger, 2010; see also Congleton & Rajaram, 2012).

In a group — what we call shared memory — the organizational and retrieval efficiency of each member affects the overall group processes. This same principle applies to both short-term and long-term memory activity and recall (Congleton & Rajaram, 2011).

This understanding represents an important development in the study of organization and retrieval processes with respect to collaborative tasks carried out in groups. The organization and chunking of a group's memory is only as good as each individual member's ability to efficiently cluster and process information. That being so, it becomes all the more critical to understand group-level retrieval organization and its relationship to the duration and extent to which shared memories are formed and remain intact (Congleton & Rajaram, 2014).

The Storage Capacity of Working Memory

Working memory is the part that processes information and therefore retains information only for the duration required for processing. Working memory is, by definition, short-term memory. It has been experimentally estimated that at most seven items can be held by working memory simultaneously (Miller, 1956).

Additional findings regarding this type of memory indicate that verbal memory is defined by phonological length: a longer word will occupy a larger portion of working memory (Baddeley, Thomson, & Buchanan, 1975; Schweickert & Boruff, 1986). This suggests that words are stored phonetically in the brain — or at least that they are clustered according to phonetic features. It follows that the duration of a spoken word, rather than the number of words spoken, should be the appropriate measure of verbal retention capacity in working memory (Vogel, Woodman, & Luck, 2001).

Brener (1940) attempted to estimate working memory capacity by presenting participants with slides of different colors in succession, one after another. Participants were then required to recall the colors in the order they appeared. Typically, seven colors could be remembered — consistent with what modern investigations have also found: seven items (in the case of verbal memory) can be recalled immediately.

In a more recent and very similar experiment, Schweickert and Boruff (1986) arrived at the same conclusion as Brener. The pertinent point is that both experiments required participants to name the colors, which means verbal working memory was activated in addition to visual memory. It has therefore proven difficult to rule out the contribution of verbal memory in experiments designed to measure visual memory alone (Vogel, Woodman, & Luck, 2001).

Sperling (1960) is credited with the first attempt to measure visual working memory capacity. Participants were asked to write down alphanumeric characters displayed briefly to them. Participants were typically able to record only four to five items. These results are open to interpretation for two reasons. First, the numbers and letters used were likely coded both visually and verbally, so the measured performance probably reflected a combination of visual and verbal working memory. Second, participants had to translate what they had seen into written form, which introduces an additional cognitive step. On both counts, the results cannot be considered definitive; nonetheless, Sperling's experiment represented a carefully designed effort to measure working memory capacity.

Conclusion

The actual structure and functioning of working memory remains largely unknown. However, this paper has clarified that working memory activity is based on the factor of attention for maintenance, and that its operating speed is very high across the many domains it covers (Vergauwe & Camos, 2014).

Processing times and maintenance demands show a mutual linear relationship. Working memory can process approximately four to five items — whether verbal or spatial (visual), such as places and scenes — at a very fast rate. Working memory is aided in its processing by domain orientation and attention-dependent parameters.

The relationship between verbal and spatial processing is clearly not interchangeable. Although verbal retention is possible even in the absence of the attention factor, no visual details can be retained without attentional resources. This distinction has important implications for understanding how memory systems operate independently yet interact within the broader architecture of cognitive psychology.