To prevent response sets or habituation, trial sequence in each block was pseudo-randomized so that subjects never had more than two trials in a row that shared the same valence, interference level, or desired response finger.
As the week progressed, the fever intensified as – predictably chosen for two Bushtucker Trials in a row – our villain was first buried in a coffin full of rats which then filled with water (drown or confess, kill the witch) before declaring herself a vegan and watching as one of the other contestants (because there are other contestants) ate the now familiar spread of animals' bits and bobs.
The randomization was controlled in order to avoid 3 trials in a row with the reward in the same hole.
When the subject made an incorrect response, the same trial was repeated a maximum of two trials in a row (correction trials).
The results showed that if CLTs remained constant for a few trials in a row, Vernier acuity performance gradually improved while changes in CLT from one trial to the next led to worse than average discrimination performance.
Conditions were pseudo-randomly ordered, with the constraint that the same condition could not occur on more than two trials in a row, and all conditions had to occur every four (for Betty and Pierre) or five trials (for the other subjects).
Trials in which subjects did not feed were terminated after 20 min. In both cases, the subject was captured and placed back in the start box, until the next trial started after 5 min. A test with a subject ended when it had fed in four such trials or when it had not fed in four trials in a row.
The critical question was whether Vernier discrimination of an upper line laterally displaced from a lower one would be affected by whether the cue-lead time (CLTs) remained constant for a few trials in a row compared to when the CLTs changed from one trial to the next.
Rather than using blocked versus random conditions we pseudo-randomized (see methods section) CLTs within blocks to look at cases where the CLTs remained the same for different numbers of trials in a row versus when they changed between trials (see [1], [14]).
If an infant balked for five trials in a row, that session was terminated.
