Fixed Response Lab Report

Yong Ho Kim
March 10, 2003

1. Describe your rat’s progress during shaping.

A mistake in the experimenter’s side must be firsthand explained in order to make sense of the rat’s behavior. I understood that the rat was not being given water until it pressed the lever by itself and assumed that the light was merely a cue stimulus to let the rat “know” that it was approaching what it was looking for – water. I convinced my labmates of this, and it is only now that I re-read the instructions that I realize that light always accompanied water and that the large delay in our rat’s shaping was due to excessively provided water.

During the initial stages, the rat approached the light hole shortly after the cue stimulus was given. Every time the rat turned its head to the direction of the switch or when the rat came close to (3 to 5 ratfeet) it, the lights went on and water provided. After moving rather randomly around the light box (I was wondering why it was that the rat had its head stuck in the box for so long), the rat came back to the middle of the box and stayed quiet. The experimenters began improvising cues to get the rat into moving, such as knocking the window next to the switch and making loud noises. The rat showed some response, and tried several times to stick its head between the glass wall and the bottom bars.

After lying down for a while, the rat again began to move around. A second shaping chance was tried again. The rat began lying its front feet on the wall more often than the first trial. Eventually it began holding the button and immediately moving over the square when the light was lit on.

2. How do you know that water was a reinforcer for today?

Providing water was a reinforcer because doing so increased the likelihood of the rat repeating the operation that became associated with water.

The rats were deprived from water, which means that there was a background negative stimulus. Letting the rats access water, which would be a neutral stimulus in regular circumstances, became a negative reinforcement because thirst was temporarily removed every time the rat performed the desired behavior.

3. Which child in a classroom would keep trying to get called on longer?

The child who almost always gets called will keep trying to get called on longer. We need to assume here that being called is a positive reinforcement. If this is granted, then it is clear that if a child was almost always called per trial then the child would associate raising his hand with being called (which we assume is a desired behavior).

4. Which type of reinforcement schedule is utilized by slot machines? Explain why it is successful.

A variable ratio reinforcement schedule is used. This makes people easily addicted because they can’t control the desire to go and give the slot machine another try by thinking “well.. I could wait till somebody tries it 15 times and then I’ll go because chances are high between the 17th and 20th time” because any instance could be the lucky instance.







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