What are the effects of these english language techniques?

The question seems to be asking for effects, so a definition of the terms isn't really that helpful. All three terms have the effect of emphasising a particular quality or characteristic of a person/object/thing. Similes and metaphors do this by ociating the "thing" with something else, perhaps something more pertinent, evocative or distinctive. Personification achieves the same end by imbibing the "thing" with human qualities, thus making it less remote a concept, and allowing for a greater degree of empathy from the reader. Of course, as is the way with much of literature, these techniques are usually employed to impact the reader on an individual level, so the question is slightly misleading.