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Chapter 6
Table 6.1
Experimental design: discrimination training
Reward context
Task cue (60s)
Discrimination stimulus (60s)
First 10s
(no reward)*
Last 50s (RI15)
Low
AÙD
A1
LL
A1
RL
1 pellet
no reward
A2
RL
A2
LL
1 pellet
no reward
VIS
V1
LL
V1
RL
1 pellet
no reward
V2
RL
V2
LL
1 pellet
no reward
High
AUD
A1
LL
A1
RL
3 pellets
no reward
A2
RL
A2
LL
3 pellets
no reward
VIS
V1
LL
V1
RL
3 pellets
no reward
V2
RL
V2
LL
3 pellets
no reward
Reward contexts were determined by wallpaper, floorboards and odour. AUD and VIS are auditory and
visual discrimination cues, respectively (white noise and house light), A1, A2, V1 and V2 refer to auditory
stimulus 1 and 2 (i.e. tone and clicker), and visual stimuli 1 and 2 (steady and flashing panel lights).
Contexts, task cues and discrimination stimuli are counterbalanced.
* The presentation of the stimulus lasted for the full duration of the trial (60s), but a response was never
rewarded during the first 10s of a trial. A trial ended with the retraction of both levers and a variable inter-
trial-interval (30s-90s)
and V1-L, V2-R) (
table 6.1
). Each session took place in one of the two reward contexts, which
determined the size of the reward earned by each ‘correct’ lever press (i.e. 1 or 3 pellets). The
order of the session (VIS followed by AUD or AUD followed by VIS) and its reward context
were counterbalanced. Further, a session consisted of 24 ‘trials’ each of which comprised a 60
s presentation of the task cue (white noise or house light indicating auditory or visual stimuli,
counterbalanced) followed by a 60 s presentation of one of the target stimuli. A1 and A2 were
each presented pseudorandomly for 12 trials during auditory sessions, and V1 and V2 were
each presented pseudorandomly for 12 trials during visual sessions. At this stage the task cues