In th is experim ent th e l i g h t — >tone + food tr a in in g (Group P) was designed to increase the a s s o c ia b ility o f the to n e , r e la tiv e to li g h t / tone + food tra in in g (Group N ). I had hoped to see fa s te r le a rn in g o f the tone-shook a s s o c ia tio n in Group P. In stage 2, however, the 2 groups d iffe re d in le v e r press suppression r ig h t from th e f i r s t t r i a l .
Thus, th e group d iffe re n c e cannot be due to le a rn in g over these te s t
t r i a l s . I t lo oks as i f the N on-predicted Group has th e same le v e l o f ^ suppression on the f i r s t 2 tone-shock t r i a l s as a t th e end o f stage 1 ;
whereas Group P shows a re d u c tio n in suppression a t the s ta r t o f stage ' 2, altho ugh th is re d u c tio n was not s t a t i s t i c a ll y s ig n ific a n t (compare
the end o f stage 1, w ith the f i r s t 2 stage 2 t r i a l s : F igures 14 and 16). D uring stage 1, Group N had is o la te d tones w ith fre e fo o d , b u t Group P always had a l i g h t s ig n a llin g the tone. Thus, w ith tone-shock p a irin g s . Group N w i l l be expe cting food, as b e fo re , b u t f o r Group P th is e xp e cta tio n w i l l be reduced as an u n sig n a lle d tone had never b e fo re been re ce ive d . I t seems li k e l y th a t th is group d iffe re n c e in suppression is an a r te fa c t o f expe cting fre e food in Group N, but n o t Group P.
A measure o f le a rn in g th a t is uncontaminated by food expectancy, is the pre-CS le v e r press r a te . I f i t is assumed th a t the background o r c o n te xtu a l cues and . th e nominal CS compete fo r a s s o c ia tiv e le a rn in g , then a re c ip ro c a l r e la tio n should h o ld ; ie , i f one group has g re a te r CS c o n d itio n in g , then i t should have le s s fe a r o f th e c o n te x t. On the fo u rth t r i a l o f te s t. Group N displayed co n sid e ra b ly more fe a r
o f th e c o n te xt than Group P. This may in d ic a te le s s tone-shock - 3 le a rn in g in Group N.
So according to th is lin e o f reasoning. Group P must have le a rn t the tone-shock a s s o c ia tio n fa s te r , although d ire c t o b se rva tio n o f th is was n o t p o ssib le because o f th e g re a te r tone-food a s s o c ia tio n in Group N. This enables me to te n ta tiv e ly conclude th a t in stage 2, the tone in Group P was being processed more than in Group N. This f i t s w ith the idea th a t E2s have h ig h e r a s s o c ia b ility i f they have been
p re d ic te d ; as suggested by the M ackintosh-type and P e a rce -H a ll-typ e id e a s.
The p u ta tiv e h ig h e r tone a s s o c ia b ility could a ls o be due to d is h a b itu a tio n . At the s ta r t o f tone— >shock t r i a l s , Group P (according to th e argument above) d id not expect fre e fo o d . This suggests the tone was being tre a te d d iff e r e n t ly in stages 1 and 2. This d iffe r e n t tre a tm e n t could w e ll a tte n u a te any e ffe c t o f CS pre-exposure. That is to say, g re a te r processing o f the p re d icte d tone could be due to a change from being p re d icte d to unp re d icte d , ra th e r than the p re d ic tiv e re la tio n s h ip i t s e l f .
This p a tte rn o f re s u lts is n o t e x p lic a b le w ith the P earce-H all and M ackintosh th e o rie s . I f a n yth in g , w ith the P earce-H all th e o ry , th e tone in Group P should have lo w e r a s s o c ia b ility than in Group N. This is because the lig h t- fo o d a s s o c ia tio n w i l l a ls o be le a m t, so th a t th e food is b e tte r p re d ic te d in Group P; le a d in g to a d e c lin e in the a s s o c ia b ility o f th e tone and li g h t . S im ila rly , according to the M ackintosh th e o ry , th e li g h t and tone in Group P compete fo r
Group N than in Group P. Thus, both these th e o rie s w rongly p re d ic t th a t Group N w i l l have g re a te r tone a s s o c ia b ility than Group P.
The Wagner th e o ry in d ic a te s th a t Group N w i l l le a rn a s tro n g c o n te x t-to n e a s s o c ia tio n d u rin g stage 1, b u t Group P w i l l n o t, as the li g h t precedes tone p re s e n ta tio n s . T he refore, in stage 2, the tone w i l l not be processed as much in Group N, and so fe a r w i l l accrue to th e co n te xt ra th e r than to th e to n e : in lin e w ith the present p a tte rn on r e s u lts .
a s s o c ia b ility , as they both a re p re d ic to rs o f the fo o d . T h e re fo re , m th e tone is a b e tte r p re d ic to r and w i l l have h ig h e r a s s o c ia b ility in