Can cognitive impairment reduce the person's ability to receive information from their environment?

Yes: It's really more complex than this, since there are many steps between stimulus, initial neurological firing, and conscious perception. All faculties have to be intact or messages from the environment don't get through without distortion. There can be processing problems with information once it gets in, even if it the initial sense organs receiving it are intact. Misinterpretations result.

Absolutely: Cognitive impairment means that parts of persons cognitive or thinking processes are impaired. This can also include perceptual disturbances or misinterpretations pertaining to information coming from the environment as well as information originating inside the persons mind.