I was able to find some time tonight to reply. Thank you for your patience.
This is a classic question of social psychology.
The answer is not as simple as it may seem. Constructivist approaches to this question state that perception and motivation is not determined entirely by external stimuli. Simply said, we perceive in a way that is more than just receiving and responding to stimuli in some universal manner. Perception can be unique, and motivation appears to be as well, even in similar circumstances.
Perception is affected by our culture, our emotions, our experiences. This is why one person sees something totally differently than another and acts with different intent, even though, argumentatively, they have seen the same thing. Example: I love all animals. You are scared of rodents. I see a mouse in the kitchen and say to you..."Look how cute." I run for a camera. You see the same mouse and scream in terror and run for a broom to kill it. Same stimulus, different motivation.
Emotions influence both perception and motivation. Studies on college students showed that teachers were perceived as taller, more attractive, more interesting when the subject matter was interesting to the student. When it was not, the perception changed.
Children near Christmas time perceived pictures of Santa Claus as larger and drew his sack of toys larger than after the holiday had past.
Even our native environment plays a part in this as well. Turnbull in 1961 studied the Bambuti pygmies who live in dense rain forests. They live in a restricted visual plain without open areas. Turnbull brought a pygmy to a large plain where a herd of buffalo was standing in the distance. The pygmy said that he had never seen these types of insects. When he was told that they were large mammals, buffalo, he was confused and irritated. But, when Turnbull drove near the animals, the pygmy was amazed when they began to grow seemingly, larger...and motivating him to become afraid. His brain literally had never processed these distances and as a result his perception was distorted and emotional motivations resulted in fear of the unknown.
Lastly, your own personal attitudes and beliefs can affect motivation and perception. Albert Ellis stated that perceptions of events combined with belief systems can motivate individuals in a wide variety of actions. For example, a student may take speech class first semester as a freshman because he/she perceives this as an easy class, motivating them to register early and attend class. Another may believe and perceive that speech class is terrifying and save it for their last class of their senior year. This is how perception can affect motivation.
I hope this has helped you,