Final answer:
In operant conditioning, 'fixed' refers to a predictable criterion for reinforcement. Fixed interval schedules involve reinforcements after set time periods, while fixed ratio schedules involve reinforcements after a set number of responses.
Step-by-step explanation:
In psychological terms, particularly within the field of operant conditioning, fixed refers to a constant and predictable criterion for reinforcement. A fixed interval reinforcement schedule means that behavior is reinforced only after a set period of time has elapsed, irrespective of how many times the behavior occurs within that timeframe. For instance, if a patient in a hospital receives pain relief medication at fixed intervals (e.g., every hour), they learn quickly that pressing the button for more medication will only yield results at those fixed times.
By contrast, a fixed ratio reinforcement schedule involves reinforcement after a set number of responses. Here the focus is on the number of responses rather than the passage of time between reinforcements. As an illustration, a salesperson might receive a commission for every set number of products sold, which encourages a consistent effort to reach the fixed quantity required for the reward.
Therefore, when we refer to fixed in scheduling within the context of reinforcement schedules, it pertains to a consistent response-reward relationship, where either a certain period must elapse (interval) or a certain number of responses must occur (ratio) before the behavior is rewarded.