EVALUATION OF THE MODAL MODEL OF MEMORY Lecturer: Dr. Benjamin Amponsah, Dept. of Psychology, UG, Legon Contact Information: bamponsah@ug.edu.gh College of Education School of Continuing and Distance Education 2014/2015 – 2016/2017
Session Overview • The session will critically examine the rationale for the existence and importance of the sensory register. We would also examine the functional distinction between the short-term and the long-term memories. Slide 2
Session Objectives • Evaluate the existence and Importance of the Sensory Register • Decide on the propriety of the distinction between STM and LTM • Evidence from Neuropsychology on the distinction between STM and LTM Slide 3
Session Outline The key topics to be covered in the session are as follows: • Topic One: Rationale and Importance of the Sensory Register • Topic Two: Distinction between STM and LTM • Topic Three: The Issue of Coding • Topic Four: Capacity Differences between STM and LTM • Topic Five: Mechanisms of forgetting and Neurological Correlates of STM Slide 4
Reading List • Ashcraft, M. H. (2006). Cognition (4 th edn.), London: Pearson Education Int. • Galotti, K. M. (2004). Cognitive Psychology: In and out of the laboratory (3 rd Edn.). Belmont, CA: Wadsworth. • Hunt, R. R. & Ellis, H. C. (1999). Fundamentals of Cognitive Psychology (6 th edn.), New York: McGraw-Hill. • Willingham, D, B. (2001). Cognition: The thinking animal . NJ: Prentice-Hall. Slide 5
Topic One RATIONALE AND IMPORTANCE OF THE SENSORY REGISTER Slide 6
Sensory Register • Since the Sensory register is precategorical and we are not aware of its existence, the following are plausible :- • Cuing a subject to report a particular kind of stimulus (e.g., letters or numbers) was ineffective, because the material in the sensory register had not yet been transferred into the STM, where the material is coded. • Sperling’s procedure is highly artificial. Human beings do not use tachistoscope in viewing at such high speeds • According to Haber (1983), why would our cognitive system depend on a component in whose use we are not skilful and which has no utility value anyway? Slide 7
Sensory Register • Obviously, having that component will have no practical value to humans since we are in the first place not aware of it. • The evidence suggests that the boundaries around the sensory register, its limits may be much blurred than was once thought. Slide 8
Topic Two DISTINCTION BETWEEN STM AND LTM Slide 9
Coding in STM and LTM • The distinction between separate storages beyond the sensory register is based on several lines of evidence. • On the issue of coding: – STM is acoustically coded, whereas – LTM is semantically coded. – Shulman (1972) showed in a classic experiment that people do have information (which is meaning based) in STM thereby arguing against the traditional view. Slide 10
Coding in STM and LTM • VISUAL CODES Some experimenters also suggest that visual codes are also stored in the short-term storage. – For example, in a Mental Rotation Test subjects have to rotate an image and decide within 30 seconds as to whether it is normal or a mirror image . – Subjects are able to decide this, which shows clearly that STM processes information about imagery. Slide 11
Coding in STM and LTM Slide 12
Coding in STM and LTM • VISUAL CODES AND LTM – Long-term memory can also be coded in less rigid ways. There is evidence that shows that LTM processes visual codes as against the only semantic codes. • LTM AND ACOUSTIC CODES – The LTM is also able to store Acoustic or phonetic codes as it is clear from our ability to remember a range of sound patterns. Slide 13
Coding in STM and LTM • We also have very large stock of memory codes for smell . For example, the smell of rotten eggs, perfume, pheromones and hot cakes are but a few examples of smells we can remember. • Clearly, we may have different codes but none exclusively characterises either the STM or the LTM. Slide 14
Topic Three CAPACITY DIFFERENCES IN STM AND LTM Slide 15
Capacity Differences between STM and LTM • One of the foundations of the STM and LTM is that of capacity. • STM has smaller capacity (7 ± ²) whereas LTM has infinite capacity. • I s this distinction valid? • If we look at the phenomenon of chunking and the relative ease with which chunking is done by most people, it argues against the idea of necessary differences in the capacities of STM and LTM. Slide 16
Capacity Differences between STM and LTM • Many people also use mnemonic devices (e.g., method of loci – strategies to facilitate retention and later retrieval of information) to code their information and that enables them to increase the capacity of the STM. Slide 17
Controlled Processes • Some useful controlled processes: – Coding – process by which external stimulation is transformed into a representation for purposes of memory. – Chunking – the formation of individual units of information into larger units. Used as a means of overcoming short-term memory limitations. – Mnemonics – Strategies or devices to facilitate retention and later retrieval of information. Slide 18
Controlled Processes – Attention – is described as a spotlight that focuses your awareness on a subset of what is going on in your head or in your environment. Slide 19
Topic Four MECHANISMS OF FORGETTING /NEUROLOGICAL CORRELATES Slide 20
Mechanisms of forgetting and Neurological Correlates of STM • Mechanism of Forgetting (Decay or Interference) – We have noticed that decay occurs in the STM whereas interference occurs in the LTM . – Unfortunately, this distinction has come under scrutiny. – In a series of controlled experiments Keppel and Underwood (1962) subjected their subjects to practice on two trials and in a replication study, subjects performed the task without practice. Slide 21
Mechanisms of forgetting and Neurological Correlates of STM – They concluded that at least some interference seems to be involved in forgetting from STM. – Again Keppel and Underwood have shown that there was some interference in the Brown- Peterson’s experiment. – Remember, there was Rehearsal Prevention Task (RPT) as part of the experimental procedure. – The RPT itself constitutes interference. Slide 22
Neurological Correlates of STM/LTM • Neurological Correlates of Short-term Memory • Do STM and LTM occupy different locations in the brain? • Interestingly, the answer to the question is both yes and no. Slide 23
Neurological Correlates of STM/LTM • Experiments with monkeys using Spatial Delayed-response Task (Goldman-Rakic, 1987) indicate that neurons in the frontal lobes act like “pointers” to LTM representations stored in more posterior areas of the brain. • Studies using PET (Positron Emission Tomography) has also revealed that the patterns of activation seen in monkeys can also be found in human subjects performing similar tasks. • Based on this research, information “in” STM is really just information stored in LTM that is under active consideration by conscious processes. • Slide 24
Neurological Correlates of STM/LTM • Currently, the neural finding suggests that instead of acting as a place for the temporary storage of information, STM is better thought of as a set of processes that works with information stored in LTM. Slide 25
Sample Questions • Describe the argument for separate systems of short- and long-term memories. • Why have so many theorists become increasingly sceptical of the structural distinction between short- and long-term memory? • What does the emerging field of cognitive neuroscience say about short-term memory? Slide 26
References • Haber, R. N. (1983). The impending demise of the icon: A critique of the concept of iconic storage in visual information processing. The Behavioral and Brain Science, 6, 1-54. • Keppel, G., & Underwood, B. J. (1962). Proactive inhibition in short-term retention of single items. Journal of verbal learning and verbal behaviour, 1, 153-161 • Shulman, H. G. (1972). Semantic confusion errors in short-term memory. Journal of Verbal learning and verbal behaviour , 11, 221-227. Slide 27
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