According to my research, yes you can...

'alpha waves
Alpha waves are oscillating electrical voltages in the brain. They oscillate in the range of 7.5-13 cycles per second. Because alpha waves occur in relaxed states such as meditation and under hypnosis, they have been mistakenly identified as desirable. Alpha waves also occur under unpleasant conditions and when one is not relaxed.* They are not a measure of peace and serenity, nor are they indicative of an altered state of consciousness. Alpha waves are indicative of lack of visual processing and lack of focus: the less visual processing and the more unfocused, generally the stronger the alpha waves. If you close your eyes and don't do any deep thinking or concentrating on vivid imagery, your alpha waves will usually be quite strong.'

'Alpha 8Hz - 14Hz Relaxed but alert '

it seems that you are able to still focus but be relaxed, thats all that counts, visualizing doesnt have nothing to do with pr except it HELPS you relax...drink tea or something, that outta do er...