Your posture could impact your memory

April 18, 2021

Posture can affect memory, according to this study. (Unsplash/Michal Parzuchowski)

People who cross their hands behind their back when learning new sentences are less likely to remember action verbs, nouns and sentences, but their memory of visual verbs is not influenced, according to new research from scientists in Spain, France and Italy.

The study, published March 31 in Cortex, provides new electrophysiological evidence of how small changes in posture affect comprehension and memory. The study focused on individual words and sentences, using language as a way to probe conceptual memory. Data was collected from 26 students at the University of La Laguna, in Spain, though the team notes that the results are relevant for all ages. 

Participants read lists of sentences with either a manual action verb, such as "take," or an attentional verb, such as "see," while maintaining different physical poses. Half of the group rested their hands on the table in a "front posture," and the other half crossed their hands behind their back in a "behind posture." Before the participants were asked to recall the sentences, they performed a one-minute task as a distraction. Researchers collected electroencephalogram data from both phases of the trial.

Most semantic research presents words in isolation, testing participants on a single word at a time. One common issue in previous studies is that "the meaning can change depending on words that are associated" with the vocabulary in question, according to corresponding author Léo Dutriaux, a researcher at the University of Paris and the University of Trento. To avoid the association problem, the team designed this study with longer phrases. The researchers created two sets of 120 sentences for participants to learn and recall, one focused on manual action verbs and the other on attentional verbs. A control group of 60 participants judged how familiar and concrete the words were. 

Dutriaux explained that the process of choosing verbs was quite challenging because language is a limited resource, especially in the confines of this study: The verbs needed to be about the same length and frequency so that they didn't influence the results. The researchers also had to test a large number of words because electroencephalogram data is very noisy with other stimuli in the brain. The technique picks up all kinds of brainwaves, such as those that occur when participants blink at an object in the room. According to Dutriaux, in EEG studies like this one, the best way to deal with these irrelevant activities is to present one variable many times and then average all the data points. Researchers can then flatten out the unwanted signals and pinpoint the true results. 

The team analyzed their data by looking at event-related potentials, which are recordings of the brain's electric field after a specific event. In this study, brainwaves recorded 10 milliseconds after the start of a sentence or a verb gave them an inside look at how participants processed language. The researchers then looked at the frequency of brainwaves over time to see which were the strongest. 

Dutriaux told The Academic Times that he was "really amazed and happy" to see how well the study turned out. He finds it "impressive that you can observe the effect of the participants' hand posture" during both the learning and the recall process, though participants' posture changed during only the first part of the study.

Previous research showed that people's memory works better when it exaggerates small differences. "Memory is your identity because if you don't have memory, you don't have a past," Dutriaux noted. In past behavioral studies, he and his colleagues tested whether posture affects adults' memory of actionable objects. They observed a difference in participants' reactions to objects that can be manipulated, such as hammers or pens, when compared with objects that people cannot grasp, such as rugs or cars. His current work is meant to broaden our understanding of how posture, language and conceptual memory relate to one another.

Currently, Dutriaux is working on research with blind people, who have a different perception of the world and a different conceptual understanding of visual verbs, such as "observe." People who are blind still use these words but associate them with another sense. For example, blind people usually mean to "touch" when they say a word such as "see," turning visual verbs into action verbs. "For them, watching something is about exploring the object with their hands," Dutriaux noted. 

He sees this sort of  memory-related research as a very important field: In his view, it could help us "better understand how the brain stores information, and explain deficits following something like a seizure or Lyme disease." Scientists who have a better grasp of language and the brain will be better suited to helping rehabilitate people. "How the brain processes information can also inspire models in artificial intelligence and computer science," Dutriaux added.

The study, "Crossing hands behind your back reduces recall of manual action sentences and alters brain dynamics," published March 31 in Cortex, was authored by Manuel de Vega and Iván Z. Moreno, University of La Laguna; Enrique García-Marco, University of La Laguna and Universidad Europea de Canarias; Léo Dutriaux, University of Paris and University of Trento; Alix Seigneuric, Université Sorbonne Paris Nord; and Valérie Gyselinck, Université Gustave Eiffel.

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