In a study by a student at Milburn High School in New Jersey (Ng, 1998), chewing gum has been shown to increase concentration and visual-spatial memory. She experimented with the correlation between chewing gum and enhanced visual-spatial memory. She asked every one of her 50 test subjects to play a version of the game Memory, once while chewing gum, a second time without. For each subject, she compared the number of trials needed to complete the game in both conditions. She found that while chewing gum, the subjects’ accuracy and speed increased by 15% as compared to playing the game without chewing gum (Ng, 1998). Parallel to her project, we are testing memory as affected by chewing gum, but we are interested in its effects on auditory memory as opposed to visual spatial memory.

After a person or animal receives stimuli, the new information is briefly stored in an area of the brain called the hippocampus, an area of the brain. A direct relation was found between mice, which have molars and can chew, and their ability in a water maze. Older mice without the ability to chew were not able to remember how to perform the maze. Analysis of their hippocampus showed unusually excessive deterioration.

The relationship between chewing and memory is not fully understood. It is thought that chewing can release stress, because the hippocampus controls stress hormone levels in the body. If people chew less, it may cause a rise in stress hormones leading to a loss of short-term memory(Pearson).

In an experiment by Cole, Coltheart and Allard (1974) the process of short-term memorization of auditory stimuli was investigated. They found that there are two types of storage of auditory stimuli. The first is the physical code, in which the brain stores how the stimulus sounds. The second type of storage is called the name code. In this type the meaning, and not the sound, of the stimulus is memorized. This is like memorizing ‘A’ as the physical code instead of memorizing ‘a’ or ‘letter A’.

In their experiment, Cole, Coltheart and Allard recorded a series of 288 tests. These tests used 22 college age subjects who in the experiment would have to decide if the letters involved were the same or different after hearing them. Each test included two of the letters, D, P, T, C, A, E, O, or U. The letters then were spoken in either a male or female voice with a pause of ½, 2 or 8 seconds between letters. At the end of the second letter the time until a subject answered was timed. Each test included only vowels or consonants and was read by either a male or female voice, which could change in the experiment.

They found that their subjects were very accurate in determining if a letter was spoken twice in an individual test pair but they made more errors for pairs of vowels than consonants. They also found that subjects’ reaction times were faster when both of the letters were spoken in the same voice. In addition, they found that similarity of letters was determined more quickly than the difference between letters. They believe this is because the brain can match the two letters using either name code or physical code and, therefore, does not have to double check. However, if the letters are different, their physical code may be similar enough that the name code must also be checked, which takes longer and causes a 25 msec increase in reaction time.

Houlihan, Pritchard, Davis and Robinson (1997) researched the effect of smoking and nicotine on visual, short-term memory. In this project, they had twenty-one regular smokers not smoke, 24 hours prior to the test. The smokers all regularly smoked cigarettes that contained at least 1.0 mg of nicotine. In order to make sure that the smokers indeed did not smoke, they verified abstinence using a carbon monoxide detecting Breathalyzer. After the subjects had practiced, they performed three tests. Before the first test, the subject did not smoke a cigarette, before the second test he/she smoked a cigarette containing 0.05mg of nicotine, and before the third, one with 1.1mg of nicotine. In the test, a set of 2, 3, or 4 consonants was displayed on a computer monitor for ¼ of a second. In each test, after the set was shown, a single consonant was shown. Upon presenting this "probe", the subject was asked to press the right mouse button if the "probe" was shown in the previous set, the left of it was not displayed before. The researchers did these tests in two "blocks" of 150 trials each. During these tests, electrodes were put on the forehead to monitor heart rate.

The results showed that smoking the 1.1mg cigarette increased the heart rate as compared to pre-smoking and post-smoking the 0.05mg cigarette. Relative to "baseline" (no nicotine), reaction time was shorter after smoking a 0.05mg cigarette, and the reaction time was further shortened when the subject smoked the 1.1mg cigarette

Jaquith (1996) examined the relationship between a student’s aptitude and auditory short-term memory. The standardized test that she used was the Stanford Achievement Test (SAT). The researcher tested an entire school in the Southeastern United States, where the researcher collected two pieces of data. The first was the testing of the subject’s audio digit span. Auditory digits were examined by dictating a series of numbers to a student. Each digit was dictated with an interval of one letter per second. The student then repeated back the sequence to the researcher. If the sequence was repeated correctly, they were required to do the same with a new set of numbers, with one more digit than in the last sequence. This procedure was repeated until the student answered incorrectly. In this case, the researcher would give back a new sequence one digit shorter. If the student missed two in a row, the test was stopped. The digit span data that were recorded were the highest sequence length answered correctly for each student. The second was a source of data from each child’s school records, turned over to the researcher with the permission of parents, such as grade point averages and SAT scores, which were recorded. With these two pieces of data, the researchers could make comparisons of the digit span scores to the standardized test results. From this, they were able to find that as a student’s memorized length of span increased, so did their SAT scores.

We know that the ability of a subject to remember a series of stimuli, given to them either aurally or visually is based upon the size of the stimuli. A subject is only able to store 4 or 5 letter words for immediate recall (Treisman and Rostron, 1972), in addition to the length of individual words, the more words there are in a sequence the more of them will interfere with recall. This is especially true with an added sound which was constant throughout an experiment, the sound, played at the end of the sequence, would take up space in memory which could then not be used by the words (Cole, Coltheart and Allard. 1974).

It was shown that chewing gum can increase memory by 15% (Ng, 1998) and that students who have better short-term memory and are able to remember more of a sequence given aurally, have a higher grade point average and do better on standardized tests (Jaquith 1996). Because of the positive effect which the action of smoking has on memory (Houlihan et al. 1997), we believed that another repetitive mechanical task such as chewing gum, would have similar memory benefits (Murdock 1967). We believed that a subject’s memory would be enhanced by chewing gum, and that it could become a valuable tool for learning, especially in aurally presented situations.