Short Term Memory | Psychology for UPSC Optional (Notes) PDF Download

Introduction

Short-term memory (STM) occupies a crucial position as the second stage within the multi-store memory model formulated by Atkinson and Shiffrin. This article delves into the characteristics of short-term memory, examining its duration, capacity, and encoding processes. Empirical evidence supports the theories surrounding STM, shedding light on its fascinating properties and limitations. Furthermore, alternative models such as working memory, proposed by Baddeley and Hitch, provide further insight into the workings of this essential cognitive function.

Duration and Capacity of Short-Term Memory

• One of the defining features of short-term memory is its limited duration, lasting approximately between 15 and 30 seconds. During this brief period, information stored in STM can be easily lost due to distractions or the mere passage of time. This fragility highlights the importance of efficient encoding and rehearsal techniques to maintain information within the short-term memory span.
• Short-term memory also exhibits a restricted capacity, allowing for the storage of only a limited number of items at any given time. Research indicates that individuals can typically hold around seven items in their short-term memory. This notion was proposed by Miller in 1956, known as the "magic number 7 (plus or minus two)." Miller hypothesized that short-term memory possessed a fixed number of "slots" for storing items. Notably, Miller did not specify the exact amount of information that each slot could accommodate. However, the process of chunking, which involves grouping information together, allows for a substantial increase in the amount of data that can be held in short-term memory.

Empirical Evidence for Short-Term Memory

• Various studies have provided empirical evidence supporting the capacity and duration limitations of short-term memory. The investigation of capacity often involves two approaches: span and recency effect.
• Span refers to the number of items an individual can effectively retain in their short-term memory. Jacobs (1887) conducted a study employing the digit span test, encompassing letters and numbers. He discovered that participants found it easier to recall numbers compared to letters. On average, the span for letters was 7.3, whereas for numbers, it increased to 9.3. These findings align with Miller's theory of short-term memory capacity, indicating that individuals can retain a larger quantity of information when it is chunked or categorized.
• The recency effect, another method of testing capacity, examines the phenomenon where individuals exhibit a higher recall for items presented towards the end of a sequence. This effect is attributed to the recency of the information still being within the short-term memory. The recency effect provides additional support for the limited capacity of short-term memory.
• Regarding the duration of short-term memory, research conducted by Atkinson and Shiffrin (1971) suggests that it spans between 15 and 30 seconds. To preserve items in short-term memory, rehearsal plays a vital role. Rehearsal involves the repetition of information verbally, employing acoustic encoding. This process helps to maintain data within the short-term memory span for a longer duration.
• Further evidence supporting the limited duration of short-term memory comes from the Brown-Peterson technique. In this technique, participants are instructed to count backwards in 3s, effectively preventing rehearsal and retrieval possibilities. Peterson and Peterson (1959) demonstrated that as the delay increased, participants recalled progressively less information. The rapid loss of information under such conditions signifies the limited duration of short-term memory.

Alternative Models: Working Memory

While the multi-store memory model by Atkinson and Shiffrin provided significant insights into the workings of short-term memory, alternative models have emerged to offer more comprehensive explanations. One such model is working memory, proposed by Baddeley and Hitch (1974). Working memory expands on the concept of short-term memory by considering additional components involved in cognitive processing, such as the central executive, phonological loop, visuospatial sketchpad, and episodic buffer. These components collectively contribute to the storage, manipulation, and retrieval of information in working memory.

Conclusion

Short-term memory plays a crucial role in cognitive processes, encompassing limited duration and capacity, as well as acoustic encoding through rehearsal. Empirical evidence, including span and recency effect studies, supports the theories surrounding short-term memory. Furthermore, alternative models like working memory provide a more comprehensive understanding of the complexities involved in information processing. Overall, comprehending the intricacies of short-term memory enhances our knowledge of human cognition and memory systems.