integrated writing 3 .. please correct and rate!

The text
Motivation, in simple terms, is the sum of the needs and wants that cause a person to act. There are many ways that motives can be classified, but one such way is whether motives are

Extrinsic motivation is a drive to perform an activity in order to obtain a reward from outside the individual. Examples of extrinsic motives are money or any other goods and services that money can buy, as well as externally bestowed intangible rewards such as attention, approval, praise, or applause.

motivation is a desire to perform an activity for its own sake rather than for an external reward. If a person is intrinsically motivated, he or she might be motivated, for example, by a desire for satisfaction, personal pleasure, self-fulfillment, creativity, or accomplishment. Those who are motivated intrinsically tend to be happier and psychologically healthier than are those who are extrinsically motivated.

It is quite possible for someone to be offered extrinsic rewards for doing something that he or she is already intrinsically motivated to do. When someone is given an extrinsic reward for doing something that is already intrinsically rewarding, then it is quite possible for that person’s intrinsic motivation to diminish. This decrease in intrinsic motivation is called the overjustification effect. To restate, the overjustification effect is the decrease in intrinsic motivation that occurs as a result of the addition of extrinsic rewards for an activity that had previously occurred as a result of only intrinsic motivation.

the listening passage:

Let me tell you a story. It’s about someone named Marnie. As a teenager, Marnie loved to sing. She sang just because she enjoyed it; she really felt alive when she was singing. She sang at every possible opportunity: She belonged to the school choir, she sang at family events such as birthday parties and weddings, and she was even invited to sing at community events—the Independence Day picnic and such. She truly enjoyed every moment she was singing.
As Marnie grew older, she continued to sing, but she didn’t always enjoy singing as much as she had in the past. Her family, school, church, and community always expected her to sing, and sometimes she really didn’t feel like singing, but she had to because it was expected. Even though her audiences always applauded enthusiastically after her performances, her heart wasn’t always in what she was doing.

One day, after a performance, a person who turned out to be a music company executive approached her and asked her if she’d ever considered singing professionally. He even offered her a recording contract that would give her more money than she’d ever dreamed of having. She knew she should sign the contract because the money that was offered was a really incredible amount. Even though she didn’t enjoy singing anywhere near as much as she had when she was younger, she knew that the responsible decision was to sign the contract so that she would be taken care of financially. She signed the contract.

Question: How is the story about Marnie related to the material in the reading passage?

My response :

In this set of materials, the reading passage gives information about the two types of motivation. While on the other hand, the listening passage gives an example to explain the two types.
In the reading passage the authors defines motivation as the sum of needs and wants that cause a person to act. He classifies it into two types; extrinsic and intrinsic. Extrinsic motivation is the desire to do something so that you can get a tangible reward for an example a trophy or money and intangible reward such as attention, praise or applause. Intrinsic motivation is the desire to do something for the sake of doing it. In other words, you accomplish something just for the love of doing it. The author mentions that those who are motivated intrinsically are happier than who are motivated extrinsically. Moreover, he says that if an extrinsic reward was bestowed on someone who was already intrinsically motivated, his intrinsic motivation would decrease. And that’s what is called overjustification effect.
In the listening passage the speaker talks about Marnie who was a little girl who loved to sing because she is intrinsically motivated. She used to sing at the church, school and community gatherings. When she grew up she was forced to sing for people because they asked for her presence. One day a music executive attended one of her shows and he liked her singing skills, he asked her to sign a contract with his label. First, she wanted to say no but because she needed the money so she had to say yes. Therefore, this example illustrates the conception of overjustification effect.

Thanks in advance.

TOEFL listening lectures: A university lecture by a professor of Anthropology