Olfactory Context Dependent Memory: Direct Presentation of Odorants

This method can help us answer key questions related to olfactory context dependent memory, such as whether odors need to be presented contemporaneously with targets in order to be effective mnemonic cues. The main advantage of this technique is that direct presentation of odorants allows the researcher to exercise more experimental control than ambient presentation of odorants. To prepare the olfactometer, cut the tubes to the appropriate length, and tightly secure them in place.

To control for tactile stimulation, present the tubes inside the metal bar that supports the chin rest. Then cover the top of the metal bar with tissue. Then apply the appropriate amount of liquid odorant onto a cotton pad and place that cotton pad within a glass jar.

After that, connect the jar to the olfactometer. When the participant arrives to the laboratory, ask the participant if they have smoked any tobacco products within the last 24 hours. Next, ask the participant if they have eaten or brushed their teeth within the past hour.

Finally, ask the participant if they have any relevant allergies. Then present the participant with the pertinent information about the study, and have the participant sign an informed consent. To control for auditory stimulation, have the participants perform the experiment in a sound-reducing cabin.

Next, seat the participant in a comfortable adjustable chair. Instruct the participant to place their chin in the chin rest, and adjust the chin rest as needed. To begin the first phase of the experiment, instruct the participant to categorize 90 total words as abstract or concrete as they appear on the screen with a button.

Begin the trial by presenting the participant with a puff of air coupled with a cross on the screen which will contain odorous material or an unscented control. Next, replace the cross with a randomly ordered target word and have it remain on the screen for 2, 000 milliseconds. When the participant categorizes the word as abstract or concrete, the next trial will be automatically triggered.

To begin the second phase of the experiment, have the participant leave the testing cabin and move to an area away from the odorous material. Then air out the testing cabin with fans. Next, instruct the participant to color in mandalas for five minutes.

To begin the third retrieval phase, instruct the participant to return to the testing cabin. Then present the participant with a cross on the screen and the same odorant used in the first phase of the experiment. Finally, replace the cross with a word and have the participant use a button press to indicate if the word is old or new.

Using this protocol, olfactory context was presented directly to test subjects. The olfactory context groups outperformed the no odor group in accuracy, thus presenting clear evidence that direct presentation of odorants can lead to context dependent memory effects. When utilizing this procedure, it is important to replace olfactory material on a regular schedule to allow for consistency of intensity and to allow for comparability with other research groups.

Following this procedure, other methods like varying the odorant presentation on a trial by trial basis can be performed in order to answer additional questions like whether odor contexts can be effective when shifted between over short times.