..and waking up to reality..

We also experimented with a heart sensor to tell how nervous a person is. The entire heart sensor consisted of a little clip, which had a bright little light bulb on one side and a light sensor on the other. The bulb would shine on your finger or on your earlobe, and the light sensor would sense the differential amounts of blood flowing through your capillaries as your heartbeats. This scheme was not very effective because our signals were very small. By looking at our heartbeat on an oscilloscope, we found that it was a very low voltage and nearly undetectable. We therefore built an amplification circuit to increase the voltage difference of our signal. Unfortunately, the circuit was not effective. Also, it seemed to matter what magnitude of resistance each individual person had. Additionally, certain members of our group had no detectable heartbeats! We finally decided that this setup was too insensitive and finicky, and so we reluctantly gave up and went back to using the copper plates.

We designed a prototype that included two copper plates per person, which is similar to a GSR (galvanic skin response) setup. When we realized this, we built two strap-on Velcro electrodes to measure the GSR. They had a more consistent connection with the skin compared to the copper plates, and were easier to move around. We then set out to measure the average range values for embarrassment by asking each other different questions and recording the typical values that were registered. This was a rather difficult process as the sensors were very sensitive to changes in pressure at the contact point and how sweaty your hand is initially. Also, we found that even seemingly innocuous questions sometimes gave relatively alarming values. However, after reading up on GSR literature, we realized that certain questions, words or phrases may trigger unconscious responses that lead to a large GSR.

We then went through several iterations in deciding how to best utilize our Crickets and the placement of our sensors, displays and motors into the various ports. Crickets are programmable chips developed by the Playful Invention Company. We found that using only one Cricket was insufficient. At the very least, we needed two Crickets that are in communication with each other via IR. The setup of our Crickets was largely dependent on the program and its limitations. Finally, we decided to have the two GSR sensors and two switches on one Cricket that sends the GSR readings to the second Cricket carrying the two displays, the light sensor for the shaft-decoder and the motor. Thus, Cricket One measures the GSR when the switch is pressed and computes the readings before sending the value to Cricket Two. Cricket Two then displays the value on the numerical display before sorting it into the four different “shame” ranges.