Turn On Your Mind: Four Decades of Great Psychedelic Rock is a history and critical examination of rock's most inventive genre. Whether or not psychedelic drugs played a role (and as many musicians say they've used them as not), psychedelic rock has consistently charted brave new worlds that exist only in the space between the headphones. The history books tell us the music's high point was the Haight-Ashbury scene of 1967, but the genre didn't start in San Francisco, and its evolution didn't end with the Summer of Love. A line can be drawn from the hypnotic drones of the Velvet Underground to the disorienting swirl of My Bloody Valentine; from the artful experiments of the Beatles' Revolver to the flowing, otherworldly samples of rappers P.M. Dawn; from the dementia of the 13th Floor Elevators to the grungy lunacy of the Flaming Lips; and from the sounds and sights at Ken Kesey's '60s Acid Tests to those at present-day raves. Turn On Your Mind is an attempt to connect the dots from the very first groups who turned on, tuned in, and dropped out, to such new-millennial practitioners as Wilco, the Elephant 6 bands, Moby, the Super Furry Animals, and the so-called ''stoner-rock'' and ''ork-pop'' scenes.