The Different Memory Systems Humans Use

Introduction

This paper encloses two purposes; the first being to outline the different memory systems humans’ use and describe the memory systems in each. The subsequent purpose is to explain the formation of memories. This paper will touch on different cognitive theories regarding the concept of a multi-store memory system in human memory and will use neurological evidence to support each corresponding system. Though many psychologists have constructed models to express human memory, this paper acknowledges Atkinson and Shiffrin’s proposed view of the sensory stores, Baddeley and Hitch’s proposed concept of working memory which replaces short-term memory and Squire’s Taxonomy of memory that is used to describe the functional system in place in long-term memory (Hunt & Ellis, 2004). This paper will also explain how memories are formulated within three stages; encoding, storage and retrieval, in a systematic fashion (Eysenck & Keane, 2005).

The Different Memory Systems Humans Use

The multi-store memory system suggests that humans possess at least three forms of memory; sensory memory, working memory and long-term memory (Martin, Carlson & Buskist, 2010). The modal model erected by Atkinson and Shiffrin subdivides sensory memory into each sense modality. This model incorporates the ideas of Baddeley’s working memory by subdividing it into three systems; the central executive and its two slave systems the phonological loop and the visuo-spatial sketchpad. Working memory can also be explained in terms of capacity and duration (Radvansky, 2006). Squire’s memory taxonomy suggests that long-term memory is subdivided into declarative and non-declarative memory (Hunt & Ellis, 2004).

Description of the Memory Systems Humans Use

Sensory Memory

Sensory memory consists of preserved information that has just been perceived, for example, a lasting copy of an image that was briefly seen or an echo of a sound that was momentarily heard. Though humans may have a sensory memory for each sense modality, researchers predominantly focus on three forms: the iconic, echoic and haptic memory (Radvansky, 2006).

Working Memory

Baddeley and Hitch (1974) proposed a model to explain the transmission of information from sensory to long-term which is known as working memory. Working memory is a holding store used for cognitive work such as reasoning and problem solving but is limited in both capacity and duration (Hunt & Ellis, 2004). This model contains three components; the phonological loop, the visuo-spatial sketchpad and the central executive.

        The phonological loop is composed of a store for verbal material and a sub-vocal rehearsal component called the articulatory loop. Neuroimaging studies on brain-damaged patients JB and TO show these components to be in separate regions of the brain (Eysenck & Keane, 2005). The phonological loop is supported by the phonological similarity effect which found serial recall to be 25% worse with a phonologically similar word list. The causation is related to the challenge in remembering which words have been rehearsed and which still need to be rehearsed by the articulatory loop in order for accurate recall (Larsen et al., 2000). Word length effect is also related to the phonological loop with memory span being governed by the rate of rehearsal. Though individuals with an impaired phonological loop tend to cope well, it is suggested that its function is to learn new words rather than to remember familiar words (Eysenck & Keane, 2005).

        The visuo-spatial sketchpad is concerned with both visual and spatial information. Its functions include the construction, maintenance and manipulation of mental images. Visual scanning, mental rotation and boundary extension are some phenomena of the visuo-spatial sketchpad (Hunt & Ellis, 2004). Similar to the word length effect, people find it more challenging to maintain complex images than simple images (Kosslyn, 1975).

        The central executive is the controlling mechanism for the slave systems. It performs operations required by the active task as well as allocating capacity in the working memory systems. It is considered to be the most significant and versatile component of the model, yet the least studied (Andrés et al., 2008). Dual-task performances, random generation and selective attention operations are used to help understand the functional role of the central executive (Baddeley, 1996).

Long-Term Memory

Squire (1991) provides a theory for the classification of long-term memory. Squire’s taxonomy is composed of declarative and non-declarative memory. In declarative memory such as semantic and episodic, retention occurs by consciously experiencing an event. Non-declarative memory on the other hand is retained through performance rather than conscious awareness (Rovee-Collier, Hayne, & Colombo, 2001).  Access to declarative memories tends to be intentional, effortful and occasionally impaired compared to that of non-declarative memories. Being able to retrieve some but not all aspects of a declarative memory is known as the tip-of-the-tongue phenomenon (Burke et al., 1991). Fragmented picture identification, word stem completion, priming and classical conditioning are some tasks conducted to classify non-declarative memory. More common tasks such as word recall and paired associate learning classify declarative memory.