Experiment code:
Per_Easy
Per_Hard

Introduction & Research Question:
This study aimed to assess the relative contributions of associative learning and US sensitisation in an electrodermal variant of the Perruchet effect. In order to do this two counterpart experiments were run, ‘Per_Easy’ and ‘Per_Hard’. In the Perruchet effect a single stimulus (the conditioned stimulus, CS) is paired with a second stimulus (the unconditioned stimulus, US) on half the trials and on the other half the trials the US is not presented. Conditioned responding to the CS is typically found to dissociate from conscious expectancy for the US. In each experiment (Per_Easy and Per_Hard) there were two CSs, two different coloured squares, in Per_Easy these were easy to discriminate between and in Per_Hard extremely difficult to discriminate between. In both experiments one CS was always presented with the US and another was never presented with the US. The degree of similarity between the two CSs was varied in the two experiments to allow for assessment of associative learning and US sensitisation in these experiments. 

Participants:
Per_Easy: 21
Per_Hard: 28

Experiment Software:
E-Prime, LabChart

Method:
Skin Conductance Response (SCR) calibration procedure: The left hand was cleaned and the the SCR electrodes were attached to the medial phalanges of the third and fourth fingers of the left hand. The US in this experiment was an electrical shock, the shock electrodes were attached to the proximal and medial phalanges of the left index finger. Participants set their own shock level in the range of 5-20mA. Participants were required to sit quietly for several minutes to allow SCR to return to baseline. 

Experimental procedure: Participants were presented with a CS on every trial for 5 seconds, on half the trials the US occurred and on the other half it did not. Changes in SCR were continuously monitored throughout the experiment. Participants were required to make an expectancy rating on each trial during the presentation of the CS about the extent they believed the US would occur on that trial. In between the two blocks the participants were given a comfort break and the second block proceeded in the same fashion beginning with SCR calibration. 

Experimenter:
Amy McAndrew

Location:
228-1
Washington Singer Laboratories, University of Exeter

Date:
November 2012-January2013

Data file format:
.csv

Data file names:
There are 4 files for each participant in each experiment, a SCR file, an expectancy (EXP) file, and two sequence files.
Per_Easy_SCR_Px (Contains each SCR response for each trial, for each trial three different values were recorded).
Per_Easy_EXP_Px (Contains each expectancy rating for each trial).
Per_Easy_Seq1_Px (Contains the sequence of trials for block 1).
Per_Easy_Seq2_Px (Contains the sequence of trials for block 2). 

Note the same data file code names were used in the Per_Hard experiment, just with Easy replaced by Hard.