The write-ups for the cognitive labs are due Friday. Please follow these guidelines.

1. Take each of the following cognitive lab tests: “modality effect,” “memory span,” “brain asymmetry,”  “irrelevant speech” and “Stroop Task.”

2. Read the short descriptions below for each of the tests. Be sure to identify the hypothesized results for each. In your write-up include the hypothesized results as well as the actual results from your test. Did your results confirm or contradict the predicted results? Include the summary results from your test and the graph (if available).

Here is an example for the modality effect test taken by Stew Dent.

When a list of items is heard (as opposed to read silently), people usually are very good at remembering the final list item. This advantage and recalling just the last one or two items when the list is heard is called the modality effect.
The modality effect predicts that recall of the last one or two items in the Auditory condition will be more accurate than recall of the corresponding items in the Visual condition.

Here are my results:
Serial Position Auditory Visual
1.0 80.0 100.0
2.0 86.666664 80.0
3.0 60.0 80.0
4.0 86.666664 80.0
5.0 73.333336 66.666664
6.0 66.666664 60.0
7.0 73.333336 46.666668
8.0 86.666664 73.333336

My results confirm the modality effect prediction. In fact, the auditory condition was more accurate than the visual condition for the last five serial positions. The scores for the 7th and 8th position were auditory-73.3% visual-46.7% for position 7 and 86.7% auditory and 73.3% visual in the 8th position.

Description of the Tests

Modality Effect
People often have to recall a series of items in order, such as a phone number. When the list of items is heard (as opposed to read silently), people usually are very good at remembering the final list item. This advantage in recalling just the last one or two items when the list is heard is called the modality effect.
Modality effects can be seen with presentation modalities other than auditory (hearing). Lists that are lip-read or silently mouthed also produce an advantage for the last one or two items compared to silent visual presentation.
These effects have an enormous influence on the development of sensory memory. This memory system is supposed to store raw, unanalyzed sensory input. It can be thought of as a back-up system: If the information in this store is useful, recall can be enhanced.
The best explanation is that auditory presentation leads to an additional type of information compared to visual (Neath & Surprenant, 2003). When trying to recall the last item in the list, you are more likely to be successful if you also have some information about how the list sounds.

Memory Span
Many theories of cognition propose that there is a short-term or working memory system that is able to hold a limited amount of information for a short period of time. The memory span experiment is one measure of working memory capacity. In this experiment, participants are given a list of items and asked to recall the list. The list length is varied to see at what list length participants will make few errors. That list length is the memory span for that subject on that task. Individuals with larger memory spans can better keep in mind different stimuli, and this seems to give them an advantage for a wide variety of cognitive tasks. Memory span has been linked to performance on intelligence tests, standardized tests, reading skills, problem solving, and a variety of other cognitive tasks.
The very existence of short-term memory is largely based on memory span types of experiments, as it was noted that memory span was approximately seven (plus or minus two) for a wide variety of stimuli. This suggested a simple storage system that held approximately seven items. Later studies demonstrated that memory span could be systematically influenced by a variety of stimulus characteristics. For example, when the stimuli are letters that sound alike (e.g., d, b, p, t) memory span is shorter. Likewise, memory span is shorter for lists of long words (e.g., encyclopedia, refrigerator) than for lists of short words (e.g., book, stove). These findings have suggested that the capacity of short-term memory is controlled by verbal processes. This experiment allows you to measure your memory span for a variety of stimulus types.

Brain Asymmetry
You may have heard that each person has two distinct hemispheres of the brain, with different capabilities. For example, the sensory signals from the left side of your body are sent to the right hemisphere of your brain and the sensory signals from the right side of your body are sent to the left hemisphere of your brain. Likewise, control of your right arm and leg is via your left hemisphere and control of your left arm and leg is via your right hemisphere. More notable cognitive differences also exist.
The left hemisphere is said to deal with language and analytical thought, while the right hemisphere is said to deal with spatial relations and creativity. The basis for these claims about cognition comes from investigations of clinical patients who, usually to control a serious case of epilepsy, underwent surgery that separated their left and right hemispheres. (This surgery prevented epileptic seizures from passing from one hemisphere to the other.) Careful studies of these split-brain patients revealed fascinating properties about how the brain was organized. A patient asked to fix on a spot on a screen could verbally report words flashed on the right side of the screen. (Those words were sent to the left hemisphere.) The patient could not say the word if it was flashed on the left side of the screen (thus sent to the right hemisphere). Notably, the patient could identify, by picking up with the left hand, a physical item matching a word flashed on the left side of the screen.

Subsequent work showed a variety of differences between the brain hemispheres, and some researchers concluded that even people without split brains effectively have two competing brains. These conclusions were picked up by the popular press, and one now sees a variety of claims that schools should nurture one brain side instead of another, or that different types of therapy should be used to strengthen an undeveloped hemisphere.
Some of these claims appear in very odd places. For example, unrelated research suggests that Mozart’s music stimulates creativity and intelligence in children. One CD jacket claims that Mozart’s music stimulates the left brain to improve logical skills. It suggests positioning the speakers on the child’s right side (presumably so the sound goes to the left brain). It is nice music and may help improve logical skills, but the left brain/right brain difference does not necessarily have anything to do with it. Moreover, sound will go in both ears and reach both hemispheres, so positioning the speakers on one side versus another cannot possibly make much difference.
As it turns out, many experiments fail to find much difference at all between the two hemispheres in normals (individuals without split-brain surgery). This is not to suggest that there are no differences, but the functional significance of these differences may be very slight. Moreover, when such differences do exist, they tend to be strongest for right-handed males. Females and left-handed individuals tend to not show brain-side effects nearly as well.
Strong evidence for brain asymmetry would be found if Shape left Response Time was faster than Shape right Response Time and Word left RT was slower than Word right RT.
On this experiment, the expected effect should be weaker for left-handed people than for right-handed people because the former show fewer differences between the left and right hemispheres.

Irrelevant Speech Effect
When people are asked to recall a list of items, their performance is usually worse when the presentation of the list is accompanied by irrelevant speech. The speech does not need to be in a language that the subject knows, and doesn’t even have to be real speech. Nonsense speech (such as “ba da ga”) works just as well.
One reason that this phenomenon, known as the irrelevant speech effect, has attracted a lot of attention is because it seems strange that auditory information (the irrelevant speech stimuli) would interfere with visual information (the items you are trying to remember).
Although there is still no generally agreed upon explanation for this effect, there are at least three different explanations (Neath, 2000). One theory attributes the disruption to interference in working memory. The visual items are translated into a phonological code that is stored in the same part of memory (the phonological store) as the irrelevant speech. Another attributes the effect to a disruption of order information. You remember the items, but it is information about the order that is lost. A third attributes the effect to a combination of two factors, an attentional component and an interference component.
This experiment predicts that you will recall the letters more accurately in the quiet condition than in the irrelevant speech condition.

Stroop Effect

When you first learned to tie your shoelaces, you needed to think carefully through each step of the process. Now, you probably do not even think about the steps, but simply initiate a series of movements that proceed without any further influence. When a behavior or skill no longer requires direct interaction, cognitive psychologists say it is automatized.
Many behaviors can become automatized: typing, reading, writing, bicycling, piano playing, driving, etc. Automatization is interesting because it is an important part of daily life. We perform a variety of automatized behaviors quickly and effortlessly. In some cases, people report that they do not consciously know how the behavior is performed, they just will it to happen and it does happen.

To explore properties of automatized behaviors, cognitive psychologists often put observers in a situation where an automatized response is in conflict with the desired behavior. This allows researchers to test the behind-the-scenes properties of automatized behaviors by noting their influence on more easily measured behaviors. This demonstration explores a well-known example of this type of influence, the Stroop effect.

Stroop (1935) noted that observers were slower to properly identify the color of ink when the ink was used to produce color names different from the color of the ink. That is, observers were slower to identify red ink when it spelled the word blue. This is an interesting finding because observers are told to not pay any attention to the word names and simply to report the color of the ink. However, this seems to be a nearly impossible task, as the name of the word seems to interfere with the observer’s ability to report the color of the ink.

A common explanation for the Stroop effect is that observers (especially college undergraduates) have automatized the process of reading. Thus, the color names of the words are always processed very quickly, regardless of the color of the ink. On the other hand, identifying colors is not a task that observers have to report on very often and, because it is not automatized, it is slower. The fast and automatic processing of the color name of the word interferes with the reporting of the ink color.

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