Proefschrift_Holstein

Chapter 6

Table 6.1 Experimental design: discrimination training Reward context Task cue (60s)

Discrimination stimulus (60s)

First 10s (no reward)* A1  LL  A1  RL  A2  RL  A2  LL  V1  LL  V1  RL  V2  RL  V2  LL  A1  LL  A1  RL  A2  RL  A2  LL  V1  LL  V1  RL  V2  RL  V2  LL 

Last 50s (RI15)

1 pellet no reward 1 pellet no reward 1 pellet no reward 1 pellet no reward 3 pellets no reward 3 pellets no reward 3 pellets no reward 3 pellets no reward

AÙD

Low

VIS

AUD

High

VIS

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

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