In one study, students were given two problems to solve. the first problem involved radiation and a tumor, the second involved a general and a fortress. students rarely saw that the solution to the second problem could be used to solve the first problem because the two problems seemed too different. being distracted by the superficial features of a problem is the obstacle to problem solving known as

there is an explationation of this on a site called crash   course world history 1

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.