There's a native and a foreign type. Native thoughts are generated internally and include things such as the inner monologue, opinions, and feelings. Foreign thoughts are ingested (through the ears, eyes, etc) and thus not automatically assimilated into the thought train to be processed. However, my brain inspects but does not process the thought without approval. I believe this is why I can be completely unaffected by things sometimes, as I simply reject its admission. This way of thinking makes it slightly hard to read, as I need to first ingest the words and then translate them into a stream of thoughts.