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The Stroop task is a color-word naming task consists of 3 separate parts:

1. Reading color words

2. Naming colors of non-word stimuli (rectangles)

3. Reading color words (congruent)

4. Naming the color of a word that describes a color but is printed in a different color. This condition is an incongruent set of stimuli and requires inhibition of our automatic mental reading abilities. Therefore, it requires more time (i.e. response time) to name the colors.

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Recording of the exact timing and accuracy of each word, however, is difficult in the laboratory. The instructions are to name the colors as fast as possible without making mistakes. Different people will use different strategies and trade off one vs. the other. They also self-correct a lot when they say the wrong color. In our case, we record the total time of each block (condition) and the accuracy. However, what is most important to us is not the exact cognitive performancethere was a set time for each block. If participants finished the list before the block ended, they could manually discontinue by pressing a button. The block will then be shown as ended in Acqknowledge. However, if the participant took longer than the provided time, they were cut off in the middle of the naming list. We are not interested in the exact cognitive performance (i.e. time and accuracy), but the physiological reactions to this task, as it is cognitively demanding and therefore more “stressful”.

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OSA 2019: OSA vs. CONTROL

OSA2013: OSA vs. CONTROL

OSA2010: OSA vs. CONTROL

Signals

1. Blood pressure

2. Respiration as a control to verify the timing of signals 1; i.e. while we don’t have exact timing of the onset of the spoken words, the respiration signal tells us roughly when the person inhaled before speaking.

3. The cardiac signal makes less sense to investigate, since it’s highly affected by the word speaking.

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1. Copy raw data into shared folder → copy to local folder

2. Separate the Stroop task and save as a separate file (keep about 90 seconds before and after Stroop block wherever possible)

3. Create focus areas for each task/file:

   1. Color naming

   2. Word readingColor naming

   3. Incongruent word-color naming

4. Run blood pressure signal detection and manually correct markers for each focus area

   1. Export excel spreadsheet with blood pressure data: systolic and diastolic

5. Run respiration peak detection and manually correct markers

   1. Find cycle inspiration-to-inspiration to get breath-to-breath breathing rate

   2. Find cycle inspiration-to-expiration for inspiration time

   3. Find cycle expiration-to-inspiration for expiration time

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Import excel spreadsheets into Matlab

Analyses to answer the following research questions:

What is the difference between breathing rates* for

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Word reading vs. color naming vs. incongruent vs. rest period: repeated measures ANOVA and simple effects analysis (i.e. which conditions differ significantly)

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Research questions

1. Does blood pressure differ between rest, congruent and incongruent conditions of the Stroop task?

2. Do OSA patients respond differently to the Stroop than healthy controls?

3. Can the differences be explained by the breathing/speaking rate of the Stroop task?

Analyses

Repeated measures ANOVA:

1. Within-subject factor: condition

   1. Word reading

   2. Color naming

   3. Incongruent

   4. Rest period

2. Between-subject factor:

   1. OSA vs. healthy control (HC)

3. Dependent variables:

   1. Breathing rates

   2. Inspiratory duty cycle (inhale/(inhale+exhale))

   3. Systolic blood pressure

   4. Diastolic blood pressure

   5. Mean blood pressure

Correlations:

1. Breathing rate per condition X blood pressure per condition

2. Breathing rate difference (congruent - incongruent) X blood pressure (congruent - incongruent)

3. Are the differences in correlations between OSA and healthy controls significant?