A Cognitive Paradigm to Investigate Interference in Working Memory by Distractions and Interruptions

The goal of the following experiment is to prove the neurobehavioral impact of distraction and interruption on working memory. This is achieved by developing a set of working memory test stimuli and interfering stimuli that will be used to probe delayed recognition, working memory. As a second step for neuroimaging experiments, observe the neural impact of passively viewing the working memory stimuli and interfering stimuli to establish a baseline of activity.

Next, have the participant complete the working memory task in three distraction conditions. Free of distraction with the distracting stimulus is to be ignored and with an interrupting stimulus to which attention is required. Thereby enabling comparisons between these different types of external interference.

The results show greater detrimental impact on working memory when faced with distracting versus interrupting stimuli, an effect that can be exaggerated with advanced age. In addition, we find neural processing differences between interference conditions and identify several neural markers that predict working memory performance. These findings are based on behavioral EEG and MRI analyses.

This method can help answer key questions in the domains of attention and cognitive control, such as how does distraction by irrelevant information in your external environment defer from interruption by information that demands your attention, as in multitasking, how behaviorally and narrowly might the resolution of these different types of interference change with aging? Before beginning this procedure, ensure that the study population has been selected appropriately. If working with older adults, conduct preliminary neuropsychological and sensory screenings such as vision and hearing.

Download and install experiment presentation software such as ePrime presentation or psycho pi onto a dedicated stimulus presentation computer. Prepare an appropriate keypad for experimental responses. Add yes and no labels to two adjacent keys, such as in the image shown here.

If performing a version of this experiment utilizing MRI, be sure to use an MR compatible keypad. This image shows the categories of stimuli that can be used for the interference in working memory paradigm. The Representative Q probe is shown in the top row and the interfering stimulus is shown in the bottom row.

For each paradigm variant demarcated by the columns high level visual stimuli will be used here for face stimuli repair, several hundred cube probe face stimuli from gray scale photos of male and female faces with neutral expression across a large adult age range. Remove hair and ears digitally and apply a blur across the contours of the face. This is the first of four working memory tasks with distinct interference conditions that will be administered in a block design.

This image shows the flow of a trial for each of the four interference conditions by RO with stimuli from the high level visual congruent paradigm variant, each rectangle depicts what is shown on the screen at a particular portion of the trial. First display a prompt instructing the participant to remember the Q stimulus. Keep it in mind and respond to the probe by indicating a match with the queue by pressing the yes key or non match by pressing the no key.

Present the queue stimulus immediately followed by a delay. During the delay, a central fixation cross is displayed on a blank screen. After the delay, present a probe stimulus.

Here base stimuli is used and collect a yes or no response. This time display a prompt instructing the participant to remember the Q stimulus and ignore the distracting stimulus while continuing to maintain a representation of the Q stimulus. Present the Q stimulus immediately followed by a short delay.

After this first delay, present an interfering face stimulus on 90%of trials. Present a face that is not male and aged over 40 years old. On the other 10%of trials.

Present a face that is male and aged over 40 years old, such as the one shown here. Immediately follow the distractor stimulus with a second short delay. Then present a probe stimulus and collect responses.

The participant should respond, yes if the probe stimulus matches the Q stimulus or no. If the probe does not match the q stimulus. Display a prompt instructing the participant to remember the Q stimulus and complete a secondary task using the interfering stimulus that appears thereafter.

In this case, the participant is asked to respond yes. If the interrupting face male and aged over 40 years old, present the Q stimulus immediately followed by a short delay. Then present the interfering interrupter stimulus and collect responses for the secondary discrimination task.

Next, present a second short delay. Finally, present a probe stimulus and collect responses as the participant responds yes, if the probe stimulus matches the Q stimulus or no. If the probe does not match, include a passive view condition during neuroimaging tasks to enable calculation of enhancement and suppression of neural activity during interrupting or distracting conditions relative to baseline activity.

When participants passively view or listen to the working memory and interfering stimuli free from task goals here, visual stimulation will again be used. Display a prompt instructing the participant to passively view all visual tasks. Stimuli Display instructions to complete the simple discrimination task.

The visual tasks instruct the participant to press a button corresponding to the direction left or right of a displayed arrow sequentially. Present or display the Q stimulus delay one interfering stimulus and delay.Two. Present an arrow in place of the probe stimulus and collect responses as the participant completes the simple discrimination task and records.

If the arrow is pointing left or right, then repeat each interference condition twice counterbalanced order. Finally, compare interference conditions using statistical software such as SPSS according to the instructions in the written portion of the protocol. These event related potential data show latency in milliseconds and amplitude in microvolts of the average evoked response in occipital temporal electrodes to the interfering face.

The event related potential component P 100 latency reveals significant enhancement to interrupters. The next two images show the correlation between the amplitude modulation of event related potential component P 100 and working memory accuracy. The amount that participants allocate attention towards an interrupter negatively correlates with their working memory performance.

Likewise, the amount of attention allocated away from a distractor positively correlates with working memory. This image shows FMRI bold activation in the fusiform face area. In response to the interfering face, the mean activation for each condition is presented in the bar graphs.

The bold response was highest in response to the interrupters and lowest to the distractors demonstrating enhanced processing of the interrupting stimuli. This image shows template and examples for neural comparisons. Measures are calculated such that a positive value always indicates greater enhancement above baseline or greater suppression below baseline for P 100 neural suppression is calculated by subtracting quantified neural activity to the distracting stimulus, and that evoked by the passively viewed stimulus enhancement is calculated in FMRI by subtracting, quantified bold activity to the baseline, passively viewed stimulus, and that evoked by the interrupting stimulus While attempting this procedure.

It's important to run this experiment in a block design with all blocks arranged in counterbalanced order for all neural experiments. Be sure to include a passive view condition in order to obtain baseline neural data. After watching this video, you should have a good understanding of how to create a cognitive paradigm probing the neurobehavioral correlates of different types of external interference during a delayed recognition working memory task.