Final answer:
The Rescorla-Wagner model suggests greater excitatory conditioning on the first acquisition trial because the surprise factor and the difference between expected and actual US effectiveness are highest at this point, leading to a strong learning episode.
Step-by-step explanation:
The Rescorla-Wagner model predicts that there will be more excitatory conditioning on the first trial of acquisition than on a trial much later during acquisition because of the principle of surprise in associative learning. According to the model, when a conditioned stimulus (CS) and an unconditioned stimulus (US) are paired for the first time, the associative strength between the two is initially zero. Therefore, the difference between the actual US effectiveness and the expected US effectiveness is greatest during the first trial, resulting in a strong conditioning or learning episode. As the conditioned responses are repeated, the CS increasingly predicts the US, resulting in less surprise and a reduced change in associative strength over successive trials.
Acquisition during conditioning can be visualized as a rising curve during the initial pairing of the CS and US, with the associative strength growing with each pairing. Subsequent trials provide diminishing returns in associative strength as the organism accustoms to the CS and its predictive value of the US, reducing the amount of new learning that occurs with each pairing, which aligns with the curve of acquisition presented in psychological studies.