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Saint Martin's University Biology Journal

May 2006, Volume 1

Short term memory retention: how time and color play a role

Kasondra J. Richman, Saint Martin's University, 5300 Pacific Avenue SE, Lacey, WA 98503. This work was supported by Saint Martin's University.

Introduction Short term visual memory is being able to recall visual stimuli that has been taken in by an individual and stored in the brain as something that is not to be permanently remembered. Short term memory differs from long term memory in that long term is just as it sounds; it is stored in the brain longer than short term memory. When you are first introduced to someone, their name is stored in short term memory and maybe gone in just a few minutes, yet information like your best friend's name is converted and stored in long term memory that can last a lifetime (Fields, 2005). Molecular biologists discovered that the conversion from short term memory to long term memory is assisted by a role that genes play (Fields, 2005). Taking a look at short term memory is important to many people such as students, professors, and even parents. For example, why is it that if students complete a lab, their professor recommends writing it up as soon as possible? Why can't a student remember all the details of that lab a week later but can remember them that evening? Or if a child tells his or her parent that they did something and then the following day a question is asked if they completed that specific task? All of these questions are related to short term memory, and examining how people take objects into short term memory may help answer some of these questions. Memory is defined as retaining and recalling past experiences using the methods of retention, recalling, and recognition (American Heritage, 2005). Based on that, visual memory retention can is retaining and recalling visual stimuli that can be recalled at a later time. If short term is added to that, a later time would be within a few minutes to a couple hours of taking in the information. Visual images are short lived but, visual memories last longer and are more enduring (Kosslyn & Shin, 1991). A visual image is a pattern that is pulled from previously stored information in what is called the visual buffer, whereas visual memories are pulled from deeper layers of the brain that hold information for longer periods of time (Kosslyn & Shin,1991). When colorful images are viewed that use natural colors rather than tones we are not used to, the images are remembered better (Jesky, 1985). So, a full color image stays in the subject's mind better than the same image in black and white (Jesky, 1985). A picture of a girl playing outside under the blue sky in a field of green grass would be better remembered than that same picture with a sky of green and a field of blue (Jesky, 1985). These "natural" colors are recognized by the brain as being normal and, therefore, are more easily remembered (Jesky, 1985). As far as a black and white photo would go, our brain is not trained, nor used to seeing things in black and white, so our brain has a harder time processing these images. According to a ScienceNow article (1997), the space limit for short-term memory recollection is seven words or digits, e.g. a telephone number. The space limit for images is four different objects. Increasing the number of images reduces the retention. This study tested the hypothesis that when given a longer amount of time to absorb information, these numbers would increase. Even when increasing the number of objects

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May 2006, Volume 1

being observed, I predicted that short term retention would increase. In a previous experiment, subjects viewed 80 slides for one second each; after the slide presentation normal classroom lecture was resumed (Pezdek & Greene, 1993). An hour and a half after class, the subjects returned and read a paper that described the previously seen slide show. The subjects were only allowed to read the paper once. Once the paper had been read, they were given two mazes to complete for ten minutes as a filler task; immediately afterward verbal and visual tests were given, but the time interval for looking at the objects was 8 seconds each (Pezdek & Greene, 1993). The task was to correctly identify images or words that were incorrect or different from the original slide show and paper. Most of the participants were unsuccessful in determining which images or words were different from the originals (Pezdek & Greene, 1993). In this experiment, there was a slide show of images presented and a short story presented, yet they had nothing to do with one another. The test, however, was about the pictures they remembered, not whether a picture was out of place in the sequence of images. The story was compared to one that was almost identical, but had minor changes, e.g. changing the color of a shirt that a person in the story was wearing. Short term memory can be impaired by stressful situations that activate an enzyme in the brain (Hampton, 2004). This enzyme is called PKC and can cause impairments in the biochemical, behavioral, and electrophysical parts of short term memory. Stress possibly played a role in my experiment when the subjects felt pressured to cram as much information about the objects as possible into their memory. The stress level was reduced by explaining to the subjects taking part in the experiment that it

was not a contest to see who could recall the most. My hypothesis was that short term memory retention could be affected by time and color. This was because of the study done by Jesky (1985), who discovered that there was a difference in how colored pictures were seen to black and white pictures. The reasoning behind time was based on the study by Pezdek and Greene (1993), who showed that between two groups of people given two different time variables one group remembered more. My hypothesis was tested by giving subjects a slideshow test along with a picture test and comparing the results between two groups. Methods Participants My participants were 21 students, staff, and faculty from Saint Martin's University who responded to an all-campus email. 15 of the participants were in the control group, and the other 6 participants were in the test group. Materials The slide show consisted of a sequence of 20 slides with each slide being related in some way. The length of the slide show was based on the study by Pezdek and Greene (1993). The narrative was a simple children's story that was a page long. This length was based on the study by Pezdek and Greene (1993). The memory test had a simple yes or no question format and asked if each slide viewed had been present in the original presentation. Color and Short Term Memory In Jesky's experiment (1985), subjects were asked to look at two pictures, one that was in black and white and another that was in color. Jesky (1985) found that a picture in color was remembered better than

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Saint Martin's University Biology Journal

May 2006, Volume 1

one that was in black and white. My experiment was conducted in a similar manner. One picture was black and white, and the other picture was in color; they were two different pictures. If I had used the same picture, I would have run the risk that the subjects remembered what they had already seen. Each picture had several things going on, but were not so over crowded as to overload the brain. These pictures were copied onto transparencies and projected onto a screen. To observe each picture, subjects were given a one minute for the control group, and 30 seconds for the test group. Following the observation time period, subjects were asked to write down everything they could remember about the picture. Five minutes were given for the subjects to write this down. The more items correctly remembered the higher the shortterm retention of the subject. All participants completed this task and viewed one black and white picture and one color picture. The control group was shown the black and white picture first and the test group was shown the colored picture first to determine whether there is a difference in which one is viewed first. Short-term visual retention For my procedure, 20 slides were selected for a slide presentation. The slides were chosen by the similarities between them. For example, they all contained people. The subjects in the control group had 15 seconds to view each slide, and the test group subjects had 5 seconds to view each slide. Another slide show was created to use for the test. This second slide show had slides added and removed to it from the original presentation; however, 20 slides were still present. The purpose of the changes and additions was to see if the subjects could recognize them. The subjects where then asked to read a one page story. A second version of the story was created.

Minor changes to the story were made and the purpose of this was to see if the changes were identified. After reading the story, subjects took a picture test, answering the corresponding questions to that picture, then were directed to read the test story. Once the story test was completed, a second picture test was taken and questions relevant to that picture were answered. Analysis Participants were separated into two categories, control and test. From there, data were arranged by the number of questions answered correctly from the tests. Ratios and percentages were calculated and presented numerically and graphically. Statistical analysis was performed on the data using the statistical software Minitab. A two sample T-test was performed to compare test results between the control group and test group and the color test and black and white tests within each group. Results For the control group the slideshow was shown twice. However, each time the responses were taken in a different manner. A two-sample t-test (Table 1) showed that there was not a difference in the manner in which the test was taken. Even though the first test was circling number I thought that there may have been a power of suggestion and that it would alter the results of the participants, however, the analysis shows that there is no difference. When comparing the control group's slideshow results with that of the test group's there was no difference (Table 2), although the control group was given longer to view the slides than the test group was. Another part of the experiment was to compare short term memory when viewing a black and white picture to that of a colored picture. When comparing the results of the control group, which were

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May 2006, Volume 1

given one minute to look at each picture, there was a difference in which one was remembered better (Table 3). The subjects remembered the colored picture better. When looking at Table 4 we can see that the control color column has larger numbers than the control B/W. Obviously, by looking at the numbers in Table 4, we can see that there appears to be a difference in the numbers. The t-test showed that there was a statistical difference with the control group's black and white picture and the color picture. However, when comparing the same scores with the test group, there was no difference (Table 5).

When you compare the control black and white to the test black and white there is no difference (Table 6). This difference could mean that the time had no effect. When looking at the control color versus test color, no difference is seen (Table 7). While the P-value, 0.092, is close to the 0.05 we are looking for, there is still no difference. This value may have been closer had I decided to keep track of each individuals result by giving each participant a number, but I chose not to do that. Had I of done that, the result may have led to a difference.

Table 1: Two-sample T for control slideshow1 vs. control slideshow2. Shown is the correlation between the first and second slideshow done by the control group. The P-value (0.765) is greater than 0.05, indicating that there is no statistically significant difference between the two versions of the slideshow tests. N 14 14 Mean 18.36 18.07 StDev 1.15 3.32 SE Mean 0.31 0.89

control slideshow1 control slideshow2

P-Value = 0.765

Table 2: Two-sample T for control slideshow 2 vs. test slideshow. Shown is the correlation between the control group slideshow and the test group slideshow. The P-value (0.648) is greater than 0.05, indicating that there is no statistically significant difference between the two groups' slideshow tests. N 14 6 Mean 18.07 17.50 StDev 3.32 2.07 SE Mean 0.89 0.85

c-slideshow2 t-slideshow1

P-Value = 0.648

Table 3: Two-sample T for control group black/white vs. control group color. This is a comparison of the control groups color picture to the black and white picture. The P-value is less than 0.05 therefore the hypothesis can be accepted since there is a statistically significant difference. N 14 14 Mean 4.00 7.64 StDev SE Mean 1.84 0.49 1.69 0.45

control B/W control color

P-Value = 0.000

Table 4. The scores for the control group's black and white and color pictures. control B/W scores control color scores 3, 6, 3, 8, 4, 6, 2, 5, 3, 5, 4, 3, 3, 1 10, 5, 5, 10, 8, 6, 6, 8, 9, 7, 7, 8, 9, 9

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Saint Martin's University Biology Journal

May 2006, Volume 1

Table 5: Two-sample T for test color vs. test B/W. This is a comparison between the test group color picture and the test group black and white picture. The P-value (1.000) is greater than 0.05 indicating that there is no statistically significant difference between the color test and the black and white test for the test group. N 6 6 Mean 4.83 4.83 StDev 3.25 1.17 SE Mean 1.3 0.48

test color test B/W

P-Value = 1.000

Table 6: Two-sample T for control B/W vs. test B/W. Shown is the correlation between the control group's black and white picture to the test group's black and white picture. N 14 6 Mean 4.00 4.83 StDev 1.84 1.17 SE Mean 0.49 0.48

control B/W test B/W

P-Value = 0.244

Table 7: Two-sample T for control color vs. test color, a comparison between the two groups' color pictures. N 14 6 Mean 7.64 4.83 StDev 1.69 3.25 SE Mean 0.45 1.3

control color test color

P-Value = 0.092

Discussion There were two questions asked in this study. How does a change in time affect short term memory? How does color affect short term memory? Starting with the time and short term memory, there was statistically no difference. This could be due to the control group having more participants than the test group. Perhaps if the number of participants were closer in each group there would have been more numbers to compare. One minute compared to 30 seconds makes no difference when looking at short term memory, because one minute and 30 seconds falls into the time bracket that is classified as short term memory. When taking a look at how color plays a role in short term memory, this is where things start to get interesting. Within each group, when comparing the color picture to the black and white picture, the color picture was not remembered better than the black and white because there was no statistically significant difference. However, I feel that if I would have kept track of each person's results by giving everyone a number and comparing their personal differences between the two pictures, I could have possibly been able to see a statistical difference. If I were to do anything different in this experiment it would be to keep track of each participant and their individual results as well as the results on a whole. Another thing that I would do differently would be to try and evenly distribute my participants more than I did. Literature Cited 2002. The American Heritage Stedman's Medical Dictionary. 3rd ed. Anonymous. Sizing up Visual Memory. ScienceNow (1997) Fields, 2005. Making Memories Stick. Scientific American: 75-81. Hampton, 2004. Stress and Memory Loss Link. JAMA: 2963.

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May 2006, Volume 1

Jesky, 1985. The Interactive Effects of Pictorial Presentation and Cognitive Style on a Visual Recall Memory Task. Diss. University of Pittsburgh. Kosslyn and Shin, 1991. Visual Mental Images in the Brain. American Philosophical Society: 524-532. Pezdek and Greene,1993. Testing Eyewitness Memory: Developing a Measure that is More Resistant to Suggestibility. Law and Human Behavior: 361-369.

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