Running head: SERIAL POSITIONING 1

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1 Running head: SERIAL POSITIONING 1 Serial Positioning: Differences Between Primacy and Recency Effects Jordan Southern Washington State University Psych

2 SERIAL POSITIONING 2 Abstract Serial positioning is the term given to the encoding and recall effects observed with lists. The primacy effect refers to recalling the items from the beginning of the list, and the recency effect refers to recalling items from the end of the list. Based on previous research, serial positioning changes when the time between encoding and recall increases (increasing the primacy effect) and is different for visual and audio encoding (no recency effect observed for visual data). The following experiment hypothesis that the correct recall of items will be higher for the items at the beginning of the list, and lower for items at the end of the list. Participants used an online program called CogLab to take the experiment, in which they were presented with a series of letters one-second each before they were to recall the letters from a list provided. The results showed a significant effect of serial positioning on correct recall; however, there was no significant difference in correct recall amounts associated with the primacy effect and recency effect. This may be due to the fact we did not adjust the retention interval (time between encoding and recall) and did not use multiple types of encoding. Serial positioning, on its own without manipulation, will not have a significant recall difference between the primacy effect and recency effect.

3 SERIAL POSITIONING 3 Introduction When a person takes in information, their brain has to make a decision on what information needs to be encoded, needs to be stored, needs to be recalled to help integrate the information all this occurs between a few milliseconds to a few seconds. One of the many forms information is distributed is in lists and the brain has learned ways to work with the information that is most efficient. All observed effects on recalling listed information, after a certain time period after encoding, has been titled serial positions. The two important parts to serial position are the primacy effect, in which the items at the beginning of the list are recalled in a high amount, and the recency effect, in which the items at the end of the list are recalled in a high amount. With the use of fmri machines, the primacy effect has been linked to long-term memory and the recency effect has been linked to short-term memory. This means the items at the beginning of a list have more time to encode into one s memory, therefore the information will be stored in long-term memory, while the items at the end of a list are still fresh in short-term memory. Since time is a key factor in memory encoding, the longer the wait between encoding of information and recall of information, the higher the likelihood that any recency effects observed are connected to long-term memory (Talmi, Grady, Goshen-Gottstein, & Moscovitch 2004). However, as this retention interval increases, primacy effects increase while recency effects decrease. As time passes after one takes in a list of items, the brain will hold onto the beginning group of items, as well as a few of the latest items, in long-term memory until such time the brain decides the information is irrelevant (Neath 1993). Irrelevancy depends on the attention and motivation levels of the person to retain the information.

4 SERIAL POSITIONING 4 Primacy and recency effects are also dependent on the way information is taken into the brain through the senses. The most common ways are through sight and sound. Conrad and Hull (1968) discovered that serial position varies for visual and audio information. They observed a virtual absence of any recency effect for visual encoding, and for good reason. Short-term memory stores information for between 15 and 20 seconds, and can hold between 5 to 9 items in that brief time period. This is for auditory information, which is the primary encoding strategy used. For visual items, only around 4 items can be stored in the 15 to 20 second time span. The information taken in at the beginning of a list will have first priority, leaving items at the end of the list unable to be encoded unless the information at the beginning has transferred over to longterm memory. When the information is auditory, more can be encoded. When the information is visual, less can be encoded in comparison. This research wouldn t have practical meaning if it weren t applied to real-world applications. Mantonakis, Rodero, Lessehaeve, and Hastie (2009) tested serial positioning with wine tasting. Participants were assigned to groups in which they tasted wines some groups only had a few wines, while others had a longer range of wines to taste. They found that participants had a strong preference for the first wines they tasted (first-is-best phenomenon). They also found that participants with high knowledge of wines preferred the last wines, especially when they tasted a longer list (expecting improvement over time phenomenon). These results show that cultural norms and evolution of the brain affect how we process information and how we handle it once it comes in. In the following experiment, we explored if serial position had an effect on correct recall. We wanted to see if items at the beginning of the list would be recalled more often, or if items at the end of the list would be recalled more often. Based on previous research, we hypothesized

5 SERIAL POSITIONING 5 that there would be a higher correct recall associated with the primacy effect, and a lower correct recall associated with the recency effect. Methods Participants There were 137 participants in this study. Age and gender were not recorded. The population pool were Cognition and Memory (Psych 490) students at Washington State University. This was a convenience sample. Participants were given the same experimental conditions. There was compensation given through class credit and all were aware of what the study was focusing on, since they had learned about the subject it in the classroom prior to the experiment. Materials The experiment was performed online with CogLab. It was available either on desktop or laptop computer, or on a compatible mobile device. Access to CogLab required purchase of a registration code, which participants had to purchase individually. Participants were given a week to complete the assigned CogLab on serial positioning, and had to do so in their own free time. Procedure Participants read the introduction, describing primacy and recency effects in memory tests and real-world settings. Participants were then instructed to view the rectangle at the bottom of the page. They would be presented with a sequence of letters, each being shown for one second. Afterwards, they were asked to select from a list of letters, in any order, the ones they recognize from the sequence. They were warned they would be unable to correct any mistakes.

6 SERIAL POSITIONING 6 This was repeated 15 times. After performing the experiment they submitted their data to the global network, were debriefed, and viewed the results of the experiment for themselves, for the class, and globally. This was a within-subject experimental design. The independent variable was the position of the words in the list, expressed in three levels the words at the beginning of the list, the words in the middle of the list, and the words at the end of the list. The dependent variable was correct recall, defined as how many correctly remembered words were selected at recall. A oneway ANOVA and Bonferroni Post-Hoc test was performed. Results There was a significant effect of the independent variable on the dependent variable, F(2, 272)=17.93, p< This means that correct recall is affected by the order the information was presented in at encoding. The post-hoc test revealed a significant difference (p<0.01) between the words remembered at the beginning of the sequence (M=0.78, SD=0.13) and the words remembered in the middle of the sequence (M=0.69, SD=0.13). There was also a significant difference (p<0.01) between the words remembered in the middle of the sequence and the words remembered at the end of the sequence (M=0.75, SD=0.16). There was no significant difference (p>0.05) between the words remembered at the beginning of the sequence and the words remembered at the end of the sequence. Refer to Figure 1 at the end of the document. Discussion We stated that a higher amount of correct recall would be associated with the primacy effect, which was not confirmed. We found that there was no significant difference between the

7 SERIAL POSITIONING 7 amount of correct recall from the beginning of the list and the end of the list. We did observe primacy and recency effects, but they didn t differ from each other. This data contradicts previous research. Conrad and Hull (1968) found that visual encoding would have a very low recency effect observed when compared to audio encoding. While our experiment did not compare these two types of encoding, we did not find any difference between the primacy effect and recency effect on correct recall for the visual encoding. Mantonakis, Rodero, Lessehaeve, and Hastie (2009) found people have a strong preference for the first wines they tasted, but our data did not show any preference for the beginning letters and the last letters presented. This may be proof of an isolated effect for the tasting senses wine tastings are a cultural phenomenon and therefore are influenced by variables outside of the brain. This would be a good path for future research in this area explore preference effects pertaining to the other senses, such as hearing music or reading books, through serial positioning testing. This study had a limited sample size that was not representative of the population. Since the participants had some previous knowledge to serial positioning, it may have affected the group data. Students taking courses studying cognition and memory use CogLab, which may mean that all the data may be an inaccurate representation of the population. We also did not take into account prior and current medical history that may influence memory encoding and recall. The likelihood of the student participants being influenced by stress, drugs, and/or alcohol is high enough that we should have taken it into account. We could have had a significant difference between primacy and recency correct recall amounts if the participants mental and physical states were more controlled.

8 SERIAL POSITIONING 8 This experiment did not explore varying retention intervals and their effect on correct recall for serial positioning. This may also explain why we found no significant difference between primacy and recency effects. Future studies should integrate in retention intervals as a second independent variable an interaction between serial positioning and retention intervals may produce a significant difference in correct recall. Based on Neath s (1993) findings, the higher the retention interval, the higher correct recall associated with primacy. Our experiment also did not explore differences between the type of encoding and their effect on correct recall for serial positioning. Future studies should compare audio, visual, and semantic encodings this should increase the chance of seeing a significant difference between primacy and recency effects. It is clear that serial positioning, on its own, has an equal rate of recall for information at the beginning and at the end of a list. Until other factors are integrated in, adjusting the encoding and recalling of the information, no difference will be observed. Serial positions are not an independent phenomenon; treating them as such in future research would be redundant and fruitfulness for furthering this scientific field.

9 SERIAL POSITIONING 9 References Conrad, R., & Hull, J. (1968). Input modality and the serial position curve in short-term memory. Psychon Sci., 10(4), Mantonakis, A., Rodero, P., Lessehaeve, I., & Hastie, R. (2009). Order in choice: Effects of serial position on preferences. Psychological Science, 20(11), Neath, I. (1993). Distinctiveness and serial position effects in recognition. Memory & Cognition, 21(5), Talmi, D., Grady, C., Goshen-Gottstein, Y., & Moscovitch, M. (2004). Neuroimaging the serial position curve: A test of single-store versus dual-store models. Psychological Science, 16(9),

10 SERIAL POSITIONING 10 Figure 1. Average correctly recalled words for letters positioned at the beginning of the list (primacy effect), at the middle of the list, and at the end of the list (recency effect).