Individual pretrial Baseline (IPB)

Definition

The pretrial baseline is the grip force value the participant needs to apply on a cell to trigger the next stimulus. It is to be sustained for a short amount of time (3s).

Several approaches to establish a pretrial baseline can be found in the literature. Most of them rely on a common value of pretrial baseline

Litterature review of GF publications and the baseline value used in the study in function of cell specifications

Publication	Cell model	Cell calibration	Total system weight (in grams)	Material of surface	Pretrial Baseline (N)
Frak & al., 2012	NC	NC	267	NC	NC
[https://www.sciencedirect.com/science/article/abs/pii/S0278262618303415 Juarez & al., 2019	NC	NC	55	aluminium	NC
[https://www.researchgate.net/publication/311279416_Portable_Device_Validation_to_Study_the_Relation_between_Motor_Activity_and_Language_Verify_the_Embodiment_Theory_through_Grip_Force_Modulation Labrecque & al., 2016	NC	NC	55	aluminium	1.5
Nazir & al., 2017	NC	NC	68	NC	1.5
da Silva & al., 2019	NC	NC	NC	NC	1.5-2
Aravena & al., 2012	NC	NC	68	NC	NC
Aravena & al., 2014	NC	NC	NC	NC	0.08-0.13 (V)
Miklashevsky & al., 2021	NC	NC	65	plastic	1.5-3
Miklashevsky & al., 2022b	NC	NC	65	plastic	1.5-3
Blampain & al., 2018	Mini40	SI-40-2	68	NC	1.5
da Silva & al., 2018	Mini40	SI-20-1	155	NC	1.5-2.5
Wilquin & Delevoye-Turrell, 2012	Mini40	NC	NC	NC	NC
Michirev & al., 2023	Mini40	NC	155	NC	NC
Miklashevsky & al., 2022a	NC	NC	65	plastic	1.5-3
Novembre & al., 2018	Nano 17	NC	NC	plastic	NC
Novembre & al., 2019	Nano 17	SI-12-0.12	NC	plastic	1-2

we need to put back the participant before the start of trial. It is important to fix an instruction of a minimum force to apply because without it participant may hold the sensor too loosely (Nazir & al., 2017).

The term of baseline to name this value can be discussed to have the more appropriate and consensual name. This can also be called a threshold.

This value was set to 1.5N in previous articles with additional informations that this value tend to decrease (18.62%) over time without instructions (Nazir & al., 2017) and there isn't a gender effect (Blampain & al., 2018).

Individual pretrial Baseline (IPB)

The Individual pretrial Baseline (or IPB) is the grip force value the participant needs to apply on a cell to trigger the next stimulus. The IPB is to be sustained for a short amount of time (3s).

New approaches

(The previous value used for baseline was based on ...) Research on grip force sensor don't modified this baseline for each participant. Due to the lack of subjectivity of this value, some questions emerged on the possible need to adjust it for each participant and the way to do it.

Lille

This method is based on a weighted mean with 2 values: comfortable holding and cell droping. The mean of the grip force signal is computed during a 60 seconds record when the only instruction given to the participant is to "hold the cell in a confortable way" following the example of the experimenter on the way to hold the cell according to the Lille setup (see image below (recup photo Olivier)). Next, we ask him to release gradually the pressure on the cell until it drops on a box full of foam (to prevent any damage on the cell). This step is repeated [3] times and we take the mean of the 3 minimum values before the cell drops.

We can compute a baseline / threshold value with 80% of the confort mean and 20% of the drop mean following this calculation:

baseline / threshold = 0.8 x confort + 0.2 x drop

Others

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