Tolman specified that the independent variables (stimuli) affect processes within the organism. these processes then control the occurrence of behavior (response). these internal processes are known as

Intervening variables

Explanation:

Intervening variables are those variables which have not been considered in the study or research but are known to affect the processes or the outcome in some way. They are normally hypothetical or hypothesized or come to knowledge afterwards and that is why they are independent variables which could not be included in the investigation from the start. Sometimes mediator variables are also referred to intervening variable. Hence, these mediator intervening variables are often used to define the relationship between the independent and the dependent variables.