Do semantic categories aid encoding?

Experimental Design and Research Methods Krystal WONG (404896)

Titles: Do semantic categories aid encoding?

Abstract:

The aim of this experiment was to examine how encoding affects subsequent memory. Eight males and eight female participants took part in this experiment. Each participant received two lists of word to memorize one was semantic meaning and one was not. It was predicted that words presented in semantic categories are easier to remember compared with words presented not in categories and semantic meaning between words. The prediction was supported. It could be explained that words which are linked together is easier to remember as they are in the same categories, participants could generate them better.

Introduction

Memory is an ability to store, retain and subsequently receive information. It can be thought of involving three main types according to Atkinson & Shiffrin (1968, 1971), which are sensory memory, short-term memory (STM) and long-term memory (LTM). Sensory memory is our initial, momentary storage of information, which last for only an instant. For example, when you are looking at a picture, sensory memory occurs as the image of the picture enters your eyes and is transmitted to the brain. Short-term memory can hold a piece of information for as long as you actively think about it. Normally people can remember7+/-2 digits on average according to Miller (1956); he presented an idea that in short-term memory people could hold 5-9 (seven plus or minus two) chunks of information. This means some people could only remember 5 digits but some people could remember 9 of them. Long-term memory can last for a lifetime; information enters long-term memory due to either repetition or intense emotion. For example, we can remember our family and friends for a lifetime. In this experiment, the information is stored according to its meaning rather than as mere sensory stimulation.

Memory is divided into three main stages: encoding, storage and retrieval. Encoding is the processing of physical sensory input into one’s memory. It is considered as the first steps in all of the three main stages. For example, a girl was kidnapped and was kept in the room where she discovered there were several numbers in the room, when those numbers entered into her memory; this is what we called encoding stage. Then before she was recovered by her parents or police, this number remains in her memory, this is the storage stage. After she was released she was able to tell the police, she remembered those numbers from storage and that is the retrieval stage. In this experiment, participants memorize a list of words by repeating them. Even though participants were played music for a minute but after that one minute, participants were still able to memorize those words.

The following experiment is designed to examine how encoding affects subsequent memory. The experiment test on whether participants can remember more words in semantic encoding condition (condition 1) than in non-semantic encoding (condition 2). In the present study, the researcher examined how semantic encoding affects subsequent memory and hypothesized that the results of condition 1, which is in semantic meaning, will have a better result. This means that participants would remember more words in the semantic list than in the non-semantic words list. The purpose of this experiment is to confirm the existing ...

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Method:

Participants

Participants were 16 students in Swansea University. There were eight males and eight females with and the average age of the participants was 22 years, with a range from 19 to 35 years. Participants gave permission to the researchers to access records for encoding. All of the participants remained anonymous to the researchers. They were told they could withdraw from the study at any time, and they were healthy and free from any obvious physical or sensory disabilities.

Materials

2 Stimulus sheets were used (condition one and condition two) in the experiment, two word lists were needed consisting 20 words each. The first 20 words are in condition one (semantic organisation) whereas the second word list displayed words randomly (non-semantic organisation). Finally 8 answer sheets were provided to participants. A radiospares electronic stopwatch model 86001295.32 was used to measure the time for encoding. Some classical music was used and written instructions were given to participants.

Design

This study used a repeat measures design. All the participants took part in both condition one and condition two. Both word lists were designed based on two principles. Firstly all of the words are shorter words, so that they are actually in the same level of difficulties. There are also two conditions for the word lists. Condition one is semantic encoding which means that the words on the list could be linked together into one category, for example, colours, subjects, cities, sports. Condition two in non-semantic encoding which means those words on the list are not from the same category, all words were listed randomly by the experimenters. The independent variables are the conditions and the dependent variables are the scores of participants as they were required to write down as many words as they could remember on the stimuli sheet during the experiments.

Procedure

This experiment took place in a controlled environment single room, only one participant take part in the experiment each time. The participant received an instruction paper in order to give them a guideline on this study. After that participants would be asked to sign the consent form and to confirm that they understood they can withdraw from the experiment at anytime.

This experiment was separated into two sessions; in the first session participants were given a stimulus sheet which includes some words on it. Half of the participants took condition one first, which is in semantic encoding; and half of the participants took condition two first, which means starting from the non-semantic encoding stimuli sheet. At the same time experimenter was holding a stopwatch, participants were given 1 minute to learn the words. After a minute passed, experimenter stopped the stopwatch and asked participants to turn over the sheet. Then some pure music would be played to participants for a minute and after that participants were asked to write down as many as the words they could remember in one minute by using the stopwatch to time. Then the first session ended and goes on to session two. In session two, again, participants were given out a second stimulus sheet, depending on which one they had done in session one. If they had done condition one in session one, then they were given out condition two stimulus sheet in this part, and vice versa. After one minute passed, participants were asked to listen some pure music for one minute like what they had done in session one. Finally they were given an answer sheet to write down as many words as they could remember in one minute. Participants were given out the debrief form and allowed to leave the experiment room. And experimenters recorded the scores for each participant.

Psychologists believed that words with high frequency and high concreteness words are easier to be remembered, for example “apple” is the word with high frequency and high concreteness and “abyss” is the word with low frequency and low concreteness. Moreover, previous results indicated the same findings which participants are expected to have better memories with high frequency and high concreteness words more than low frequency and low concreteness words.

Results:

Comparison on the results of Condition 1 and Condition 2

Figure 1. Means number of words recalled and Standard Deviation in Condition 1 & 2

The means of Condition one is 16.44(+/- 1.41) and the means of Condition two is 9.75(+/- 2.35). This difference was significant. (Related-t = 10.96, degree of freedom (d.f.) = 15, p=0.05, two tailed test)

The results came out that participants have a better memory on Condition one and they can encode more words on it.

Discussion

The hypothesis of this experiment is that participants would remember more words in condition one (semantic meaning) than in condition two (non-semantic meaning). The results are as expected which the words in semantic categories with high frequency and high concreteness are easier to be encoded.

Referring to the results found, experimenters noticed that there are some differences between participants who are Native English speakers and who are international students. The majority of international participants got higher marks in both Condition 1 and Condition 2 compared with Native English speakers. Moreover, since there is half of the participants start doing condition 1 first and half of them start doing condition 2 first, there are also differences results come out. Experimenters found out that those who start doing condition 2 first would have a better result. It could be explained by the learning effects and practice effect, as they learnt from the first part of experiment, they understood they have to encode it after a one minute music played, therefore participants learn to rehearse those words while they are listening to music next time( second part of the experiment). However, since the words in Condition 1 are easier as it is in semantic meaning, participants can get higher marks with it because of the ordering of experiments. Not only that, participants encoded those words not only based on their memories but also because all the words in Condition 1 is from the same categories therefore once they could remember the categories, they could generate all the words easily.

Furthermore, as the experiments were took place in a quiet place and there is only one participant each time in the experiment, participants will feel stress with this environment and it would affect their results on encoding. In addition, experimenters heard some feedbacks that participants do not have enough time to write down all of the 20 words even if they could remember it. (As there is only one minute for them to write out the words they could remember each time.) Participants would have higher marks if they were given 20-30 seconds more. Finally, experimenters discovered that music are affecting their memories in encoding especially if experimenters choose some pop music to them, it would be so disturbing and affecting their emotions on this experiments. It can be improved by choosing some soft music instead of pop music and perhaps classical music is a better choice for this experiment.

Psychologists believed that encoding is not simply copying information directly from the outside world into the brain. Rather, the process is properly conceived as recording. Psychologists have studied many different recoding strategies and found out people often use to remember items of information by rehearsing them or to repeat them mentally. Therefore in this experiment, if participants understand that they have to write down the words they could remember before they started doing the experiment, participants would definitely try to repeat the words mentally in order to have a better memory.

Nevertheless, there are several problems which can be solved in the present experiments. Firstly, experimenters could consider extending the time for participants to write down the words they could remember as this experiment is not aim to test how fast they could write in a minute. However, it is testing their speed in addition to memory so the time extension should not be very long as well, basically it is suggested participants should have enough time to write down those 20 words in every list. Moreover giving them more time will make them feel more relax and the results could be better in encoding. Also, as the environment is quite stressful, so it will be better if participants can start doing the experiments after they sat down for a while. For example experimenters could play out some soft music first or chat with them for a couple of minutes in order to let them relax and get used to stay in that environment.

Also, the age range of participants is too wide and it is not even in each group. The age of all participants was 19- 35 with the means age of 22. In group 1, which is doing condition one first, the age range is 19-35 whereas in group 2, those who are doing condition two first, the age range is 19-24. Because of the means of age in the first group have a higher means of age compared with the second group, it affects the final results. It is because aging will affect memories; therefore having a large range of participants is harder to have an accurate result. It is suggested to minimize the age group in the next experiment or separate participants by their ages so that it will have two group with the evenly age range and the result will be more accurate.

In addition, the numbers of participants are not enough to carry out an accuracy result as there are only 16 participants taking part in this experiment. In order to have a better results or a better explanation on how encoding affects human memory, more participants are required and should be selected from the same age groups therefore the aging problems will be solved and the results will be clearer as well.

Furthermore, compared with international students and native speaker students, as mentioned above, international students could get a higher mark on both conditions. The reasons of that could be explained by the difference of introducing the experiment. As the international students were told to have an experiment about memory, therefore they might gain the ideas of knowing that they have to remember something during the test. And once those words show to them, international participants will try to remember it first even they are not sure if they have to do that or not.

In sum, this experiment shown that participants could remember more than 7 +/-2 words as a short term memory. More importantly, the learning effect and practise effect help to have a better result in the second parts of experiments. Participants learn to rehearse those words while they were shown another word list. Therefore the practice might actually have affected on this findings. However, in conclude that words in semantic meaning is easier to be encoded compared with words in non-semantic meaning and it reached the aim of this experiments.

References

Miller, G.A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63, 81-97.

Coolican, H (2004), Research Methods and Statistics in Psychology. Fouth Edition (Table 3, P.662 )

Edward E. Smith, Susan Nolen. Hoeksema, Barbara L. Fredrickson, Geoffrey R. Loftus(Ch. 8)

Richard Gross, Psychology The Science of mind and behaviour, Fifth Edition (CH.17)