Human Memory: A Proposed System and Its Control Processes - Research Paper Example

Abstract: The serial position effect in memory recall explains why people tend to remember items most recently presented or those items from a list that are presented at the very beginning, while items in the middle are more easily forgotten. The single participant in this study had to recall six lists of words, appearing at random for 1.5 seconds. For three of the lists, words had to be recalled as soon as presented, for the other three lists, after a delay of 30 seconds. The analysis of the results indicated that for free recall, the participant was able to better recall items presented at first (primacy effect) and at the very end (recency effect). When there was a delay, the primacy effect still occurred, but the rate of recall of words presented in the middle and at the end of the list was similar. Introduction: The serial position effect results in the graphical outcome of a U curve when word recall is tested immediately after a list is presented. Words at the very beginning and end of the list are better recalled while those in the middle show poor recall. When recall is initiated after a delay, it is only items presented at the beginning of a list which are recalled, while recall is uniformly poor for items presented in the middle and at the end of the list. Aim and Objective of the experiment: The aim and objective of the experiment was to test recall of word lists, to detect whether there was evidence of the primacy and recency effect. The experiment also compared these results to those obtained when lists are presented with delayed recall. Hypotheses: There are four different null hypotheses proposed to be examined through this research study. (a) In the immediate recall task, there will be a higher level of recall of words presented at the beginning of the list rather than the middle.(b) In the immediate recall task, there will be a higher level of recall of words presented at the end of the list as compared to the middle (c) In the delayed recall task, there will be a higher level of recall of words presented at the beginning of the list (d) In the delayed recall task, there will be a higher level of recall of words presented at the end of the list as compared to the middle. Method: Participants: There was a single participant in this study, i.e, a First Year student of Psychology from ARU, who was well versed in English and had normal vision. Apparatus: This experiment used a computer that had a specific computer program presenting lists of words and the facility for the participant to respond by typing the words into the computer. Six separate lists, each containing twelve words each were used. The program also consisted of arithmetical tests used with the tests for delayed recall. Design: A within-subjects design was used and the percentage of words recalled by the participant was measured for each list, both under the immediate response and the delayed response category. The level of recall for words presented at the beginning of the list was compared to those recalled at the middle and the end of the tests. The dependent variable in this instance was the percentage of words recalled, while the independent variables were the position of the word on the list and whether it required immediate recall or delayed recall. Procedure: The six lists that were tested for recall were presented through a computer, which first questions whether the participant can type and offers the option to recall the words by typing them. Each of the six lists contained twelve words, which were presented to the participant one by one, each word for 1.5 seconds each, with a gap if 0.5 seconds between the words. At the end of each list, the participant was asked to recall the words and type them into the computer. For the first three lists, the participant was asked to recall the words immediately. For the next three lists, there was a delay of 30 seconds during which the participant was required to perform a mathematical task before trying to recall the words which had been presented in each list. These mathematical tasks were in the form of IS (19 + 12) greater than (75-24)? The participant was first required to indicate the answer to this problem by pressing the plus key for a ‘yes’ answer and the minus key for a ‘no’ answer before typing in the words recalled from the list. Results: The results obtained are shown in the tables and graphs below. A detailed table of results and T-test results is included in the Appendix. Beginning Middle End Immediate Recall 53.20619 33.59381 43.5567 Delayed Recall 45.99175 31.18351 31.54948 In the case of immediate recall, words recalled at the beginning and end are greater, as compared to those in the middle, as per the graph below. In the case of delayed recall, it is only words presented at the beginning which show high recall, while recall of words presented at the middle and end of the list is uniformly low, as shown in the graph below. A paired samples T-test was conducted to compare the two paired groups – immediate and delayed recall. The results obtained on the P values were as follows: t df Sig (2 tailed) Pair 1: Immediate recall Words at beginning Words in the middle 8.493 96 0.000 Pair 2: Immediate recall Words in the middle Words at the end -4.969 96 0.000 Pair 3: Delayed recall Words at the beginning Words in the middle 7.338 96 0.000 Pair 4: Delayed recall Words in the middle Words at the end -0.183 96 0.855 Discussion of results: The graphical results above demonstrate the serial position effect, with the primacy effect and recency effect evident in the test of immediate recall, while the test of delayed recall shows that only the primary effect operates. The results on the t-test show that for the first three pairs, the t values obtained do not fall within the critical range for the significance level of 0.000, hence the null hypotheses which have been assumed in these cases cannot be rejected. On this basis the following must be concluded: (a) In the immediate recall task, there is higher recall of words presented at the beginning of the list than the middle (b) In the immediate recall task, there is higher recall of words presented at the end of the list than the middle (c) In the delayed recall task, there is higher recall of words presented at the beginning of the list than the middle. But in the case of the last pair in the T-test, the significance level obtained is 0.855 while the ‘t’ value is -.183, which falls close to the critical range of T-values according to the critical T-values table. As a result, the null hypothesis assumed must be rejected in this case, hence it must be concluded that in the delayed recall task, the recall of words will not be higher at the end than in the middle. The results obtained in terms of three of the null hypotheses above are consistent with the serial position effect and the recall of words based on the primacy and recency effects. In this study, there was only one participant; however the results can be generalized to the larger population by using a wider participant base and an increased number of word lists, which may serve to reinforce the findings. The null hypothesis on the higher recall of words at the end of the list during delayed recall was rejected. This suggests that the recency effect does not involve the use of secondary memory as is the case with the primacy effect. Recall under the recency effect is dependent upon primary memory where limited processing is possible and the memory buffer capacity is also limited, as opposed to the elaborate encoding possible with secondary memory. As a result, any interference or delay to the operation of primary memory results in a loss of the information, which explains why words at the end of the list are recalled in the immediate recall task but recall fails when there is a delay or interruption in memory processing. References: * Atkinson, R. C., & Shiffrin, R. M, 1968. “Human memory: A proposed system and its control processes”, Psychology of learning and motivation: 2, p 249.  Read More