An internal attribution (also known as a dispositional attribution) is when an individual uses a personal reason as the cause for a situation or event instead of an external (or environmental) attribution.
For example, a person gets a bad grade on a test. They question themselves as to why they got such a bad grade. Internal attributions might be that they were tired or that they are not smart enough for the class. External attributions would that the instructor didn't teach the material well enough or that the test was too difficult. Internal attributions are a feature of attribution theory and are a characteristic of people with an internal locus of control.