<figure><img src="image_1.png" /></figure>

HAL
open science

# Effect of Induced Postural Changes on Cognitive Load

Elissa El Khalil, Sophie Lemonnier, Pauline Maurice

► To cite this version:

Elissa El Khalil, Sophie Lemonnier, Pauline Maurice. Effect of Induced Postural Changes on Cognitive Load. European Conference on Cognitive Ergonomics, Oct 2024, Paris, France. 2024. [hal-04690243](https://hal.science/hal-04690243v1)

HAL Id: hal-04690243

https://hal.science/hal-04690243v1

Submitted on 10 Sep 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# EFFECT OF IMPOSED POSTURAL CHANGE ON COGNITIVE LOAD

Elissa EL KHALIL<fnref n="1" />;<fnref n="2" />;<fnref n="3" />, Sophie LEMONNIER<fnref n="1" />;<fnref n="2" />, Pauline MAURICE<fnref n="2" />

## BACKGROUND

<figure><img src="image_3.png" /></figure>

## METHODS

<figure><img src="image_4.png" /></figure>

### Experiment : Change of posture while doing a repetitive manual task

* 23 Participants [9 ♀; 14 ♂], ¯x age = 29.9 years.

* 5 Experimental conditions

<figure><img src="image_5.png" /></figure>

* No postural change ⇒ Baseline : Fixed position.

* Change of posture ⇒ 2 main variables :

* Level : **Small** vs. **Large**,

* Type : **Predictable** vs. **Random**.

⇒ 5 mins/condition.

⇒ 15 s/box.

⇒ Change is guided by a light and a sound signal.

<table><thead><tr><th></th><th>Measures</th><th>Performance</th><th>Physical Effort</th><th>Cognitive Load</th></tr></thead><tbody><tr><td rowspan="4">Direct</td><td>Motion Capture</td><td></td><td>✓</td><td></td></tr><tr><td>Eye-Tracker</td><td></td><td></td><td>✓</td></tr><tr><td>ECG</td><td></td><td>✓</td><td>✓</td></tr><tr><td>Task Score</td><td>✓</td><td></td><td></td></tr><tr><td rowspan="2">Indirect</td><td>NASA-TLX</td><td>✓</td><td>✓</td><td>✓</td></tr><tr><td>Borg's CR-10</td><td></td><td>✓</td><td></td></tr></tbody></table>

## RESULTS & DISCUSSION

**Performance** : Scores do not show significant difference between any conditions.

Nasa-TLX score shows that better performance is **perceived** for the fixed condition than for the rest.

Level of postural change :

<figure><img src="image_6.png" /></figure>

<figure><img src="image_7.png" /></figure>

**Physical Effort** :

Borg's CR-10 : [Arms and Legs]

* Fixed position > Postural change,

* Large change < Small change.

<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

⇒ Postural change seems to be beneficial in reducing physical effort especially with large change as the whole body is engaged in the postural adaptation.

**Cognitive Load** :

NASA-TLX : [Task Load, Mental Demand and Temporal Demand]

* Postural change > Fixed position.

<figure><img src="image_10.png" /></figure>

<figure><img src="image_11.png" /></figure>

⇒ Postural change seems to have a cognitive cost that was felt irrespective of the type or level of change.

**Stress** :

RMSSD

<figure><img src="image_12.png" /></figure>

⇒ Better adaptation to stress with postural changes and for large changes compared to small changes.

**Strategies** :

<figure><img src="image_13.png" /></figure>

Posture adaptation ⇒ varying strategies depending on the level and the predictability of the change.

<figure><img src="image_14.png" /></figure>

(based on interviews and observations)

## CONCLUSION & PERSPECTIVES

* Postural variation seems to mitigate physical fatigue but might impose additional cognitive load.

* This trade-off between physical and mental demands needs to be considered in task design as increased cognitive load could affect performance and overall well-being.

* It is important to replicate the experiment with robot, as the general context of the study is collaborative work with cobots, and human behaviour is highly influenced by its presence.

## REFERENCES

* INRS. (2015). Troubles musculosquelettiques (TMS)

* Longo L, Wickens CD, Hancock G and Hancock PA (2022) Human Mental Workload: A Survey and a Novel Inclusive Definition. Front. Psychol. 13:883321. doi: 10.3389/fpsyg.2022.883321

* Yaacoub, A., Thomas, V., Colas, F., & Maurice, P. (2023). A Probabilistic Model for Cobot Decision Making to Mitigate Human Fatigue in Repetitive Co-Manipulation Tasks. IEEE Robotics and Automation Letters, 8(11), 7352-7359. https://doi.org/10.1109/LRA.2023.3315583

<footnote n="1">¹ Université de Lorraine, PErSEUs, Metz, France</footnote>

<footnote n="2">² Université de Lorraine, CNRS, Inria, LORIA, Nancy, France</footnote>

<footnote n="3">³ IfADo – Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany</footnote>