A Method for Manipulating Blood Glucose and Measuring Resulting Changes in Cognitive Accessibility of Target Stimuli

The overall goal of this methodology is to experimentally manipulate blood glucose using a fasting procedure followed by administration of a beverage. This is followed by the presentation of a method for measuring changes in implicit cognition using a lexical decision task. This method will show researchers how to experimentally manipulate participants'blood glucose levels and then program a task to measure changes in implicit cognition that results.

The main advantage of this technique is that it's relatively inexpensive and easy to perform. Although this method can be used to measure the impact of energy need on changes in implicit cognition, it can also be used to measure the impact of energy need on other psychological processes and behavior. To begin, set up a two part survey using survey building software.

In addition to the research task, make sure that the survey begins with a consent form and ends with a debriefing statement. Next, send out a recruitment email and select a pool of participants based on the inclusion and exclusion factors described in the accompanying text protocol. Ask them to refrain from eating or drinking any non water beverages for eight hours prior to their participation session.

It is critical that you instruct participants to fast for a minimum of eight hours prior to the experimental session. Any participant that violates these instructions, needs to be excluded from data analysis. Before participants arrive in the laboratory, assign each participant a unique ID number and randomly assign them a beverage type using a participant log.

Then, write each participant ID number being used in a session on an individual sticky note. Pre-pour the participant's chilled drink into an opaque disposable cup labeled with that participant's participant ID number. It's important that participants'ID numbers are correctly entered into the experimental log and their testing computer so that data can be linked at the end of the study.

On the computer, open the study folder, double click on the Batch file icon, and select Run to open the survey. Bring participants into the lab and ask if they have met the pre-agreed fasting requirements. Have the participant digitally sign the consent form before starting the experiment.

Following this, ask the participants a few short questions that will help to maintain the integrity of the cover story. When the computer screen indicates a stopping point, guide the participant to a sterile spot away from the survey to take a pre-manipulation blood glucose reading. Clean the participant's finger with a sterile wipe and then use a lancet to gently prick the side of the participant's index finger.

Squeeze a small amount of blood onto a blood testing strip, and insert the strip into a glucometer. Write down the corresponding blood glucose reading and the time that the blood glucose reading was taken in the participant log. Then, wipe down the area with a sterilizing wipe to prepare it for the next participant.

Offer the participant some hand sanitizer and a tissue to clean their finger. Also, provide the participant with a small adhesive bandage if they desire to use one to cover their finger. Following the glucose test, direct the participant to take a seat at the computer terminal.

At this point, check that the cup matches the assigned condition and participant number recorded on the participant log and hand the participant the cup containing their assigned drink. Instruct the participant that the next task will involve making a series of consumer evaluations and that they should inform the experimenter when they reach the stop message at the end of the timed beverage consumption task. Next, instruct the participant that the task requires that they consume the entire beverage in two minutes or less and that the computer will time them.

When the participant begins to drink the beverage, click the Next arrow on the survey page to begin the timed beverage consumption task. After the two minute period has elapsed, the survey will automatically continue to a message that prompts the participant to fill out the beverage evaluation questions. It will then automatically follow these questions with a filler task.

While the participant completes the task, collect the used beverage cup from the participant's work space but do not throw it away. Mark down whether or not the participant finished their entire beverage in the experimental log next to the participant's ID number. The filler task will last for 10 minutes to allow the changes in blood glucose level to occur.

Upon completion of the 10 minute filler task, a Stop message will appear. At this point the participant should submit and close the survey. Then, immediately take another blood glucose reading and proceed to the lexical decision task.

To begin the lexical decision task, double click and open the software. Enter the participant's ID number into the prompt and initiate the programmed lexical decision task by clicking the Run button on the prompt window. At this point, briefly describe the lexical decision task to the participant and instruct them to notify the researcher when the task is finished.

Then, allow the participant time to complete the lexical decision task on the computer. After finishing the task, close the lexical decision task out fully by hitting the space bar. Next, ensure that the batch file opens the final survey portion, which contains the socio-demographic questions and a debriefing statement as described in the accompanying text protocol.

At the conclusion of the entire study, debrief, compensate, and dismiss the participant. After the participant leaves, flag the data of any participant that did not meet fasting requirements, whose fasting blood glucose read higher than 100 milligrams per deciliter, or that did not finish their drink. Results of a study based on this methodology revealed that participants who drank non calorically sweetened beverages responded more quickly to high calorie words than participants who drank sugar sweetened or unsweetened beverages.

Results also revealed no differences in mean reaction time to these same high calorie words between participants who drank sugar sweetened or unsweetened beverages. In addition, there were no effects of drink type on participants'reaction times to low calorie food words or non words. After watching this video, you should have a good idea of how to experimentally manipulate participants'blood glucose levels and then measure resulting changes in implicit cognition.

These procedures can be used either together or separately and can be done in under one hour if performed properly. Don't forget that working with human blood, even in small amounts, can be extremely hazardous. Always take proper precautions such as wearing rubber gloves and using appropriate sanitation techniques when performing this procedure.