Running an Eye tracking experiment with E-Prime

When using E-Prime with a SMI eye tracker, E-Prime should communicate with iView X, the eye tracking software, to stop and stop the recording, indicate the start of each trial and save the data. The way SMI prefer to do this is using an ethernet connection and the UDP protocol, but E-Prime cannot handle this. The only way, at the moment, is by using the serial port. To do this you wil have to add the following things to your E-Prime script:

1 - Create a 'Serial' device, by going to 'Experiment object' properties, then selecting the 'Devices' tab, then 'Add' and 'Serial'. The default settings should work.

2 - At the start of your experiment, when you want the eye tracker to start recording, add these lines, in an inline object:

' Flush serial connection and clear eye tracker recording buffer

Serial.FlushOutBuffer

dim strData as string
strData = "ET_CLR" & Chr(10) & Chr(13)
Serial.WriteString strData

' Start eye tracker recording

strData = "ET_REC" & Chr(10) & Chr(13)
Serial.WriteString strData

3 - at the start of each trial, or just before your main stimulus is being presented, add a 'remark line', preferably with your stunulus name as an argument:

Dim strData As String
strData = "ET_REM " & c.GetAttrib("stim") & Chr(10) & Chr(13)
Serial.WriteString strData

4 - Finally, at the end of th experiment put these lines in an inline object:

' Stop eye tracking recording

strData = "ET_STP" & Chr(10) & Chr(13)
Serial.WriteString strData

' Save eyetracking data in a file with a subject, session etc.
dim filename as string
fileName = str(c.GetAttrib("Subject")) & "_" & str(c.GetAttrib("Session")) & ".idf"
strData = "ET_SAV C:\\" & fileName & Chr(10) & Chr(13)
Serial.WriteString strData

Obviously, the filename can be changed to whatever is best for you. Note that iView X cannot save to a directory that doesn't exist, so make sure to either create the correct directory, or write to root.