The Polygraph Place

Thanks for stopping by our bulletin board.
Please take just a moment to register so you can post your own questions
and reply to topics. It is free and takes only a minute to register. Just click on the register link

  Polygraph Place Bulletin Board
  Professional Issues - Private Forum for Examiners ONLY
  Arm Activity Sensors

Post New Topic  Post A Reply
profile | register | preferences | faq | search

next newest topic | next oldest topic
Author Topic:   Arm Activity Sensors
posted 09-19-2005 10:02 AM     Click Here to See the Profile for Guyhesel   Click Here to Email Guyhesel     Edit/Delete Message
Hi all

I see Lafayette are selling Arm Activity sensors, they look a similar version of the Piezo activity sensor except they go on the arm of the chair.

Has anyone tried them out yet?, if so do they work?

Guy H

IP: Logged

Ted Todd
posted 09-19-2005 11:19 AM     Click Here to See the Profile for Ted Todd     Edit/Delete Message

Lafayette had an old version that had a seat and two arm pads that were inflated. I don't know if the arm pads you are talking about are new or not.

I have an Axciton system and see no need for adding arm pads. Mine works great and I have heard similar comments from the people using the Lafayette sensor.


IP: Logged

posted 09-19-2005 12:36 PM     Click Here to See the Profile for Bob     Edit/Delete Message

For sometime now I have been utilizing Layfayettes piezo sensing pads, five altogether- one under each arm, one on the seat, and one under each leg. I highly recommend utilizing all of them- I acknowledge some examiners may feel this is ‘overkill’ but you will be amazed how ‘sneaky and covertly’ clients are engaging in bodily movements. Overall, I think they are much more sensitive than the pnuematic air bladder style.

I connected the two arm pads together- and are displayed on one tracing line; the legs and ‘butt pad’ are connected together and are displayed on a separate tracing line. (I would have liked to have separated them all to reflect which individual limb was being moved, but lafayette DAS unit has insufficient input channels).

Now that I fully recommend them- what I don’t like about lafayette’s software is the “automatic re-centering feature.” It is difficult to determine if the examinee ‘moved and held’ a different arm/leg position- or whether they just had a movement ‘twitch’. What both pnuematics and piezo sensors do not pick up very well is deliberate, but fine motorskilled, "movements”- those clients that do so sneaky and covertly (for example lifting an index finger slightly and holding-, or a deliberate but very slow rotation of the foot from one position to another, or switching between hands and legs). Generally there needs to be some 'pressure difference' detected by the sensors for a change to occur and register on the trace line.

With sensing pads, my experience has been cleints tend to refrain from question ‘specific’ countermeasures but go to a more ‘general state’ overall countermeasure (such as increase arm/leg muscular tension to increase blood pressure and holding) or switch to ‘mental’ countermeasures.


IP: Logged

All times are PT (US)

next newest topic | next oldest topic

Administrative Options: Close Topic | Archive/Move | Delete Topic
Post New Topic  Post A Reply
Hop to:

Contact Us | The Polygraph Place

copyright 1999-2003. WordNet Solutions. All Rights Reserved

Powered by: Ultimate Bulletin Board, Version 5.39c
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 1999.