Hi, a reaction tells you a great deal about the feelings and thoughts that person is going through. Reactions indicate if information has been understood or if its caused confusion. It can alert you to aggression or fear. This all enables you to react or respond appropriately to the individual eg. If the message you are delivering is not understood you can adapt the way you provide it - use different language/words, visual resources eg. documents, letters, images, show a form that needs filling out. It also provides a way for the setting to see if it needs to find other materials that support effective communication eg. leaflets in languages other than English, large print and tactile, braille for sight and hearing impairement.