1965. With members who had been part of the cafe-based folk scene in Los Angeles, the Byrds adopted rock instrumentation, including drums and 12-string Rickenbacker guitars, which became a major element in the sound of the genre. Later that year Dylan adopted electric instruments, much to the outrage of many folk purists, with his "Like a Rolling Stone" becoming a US hit single. Folk rock particularly took off in California, where it led acts like The Mamas & the Papas and Crosby, Stills and Nash to move to electric instrumentation, and in New York, where it spawned performers including The Lovin' Spoonful and Simon and Garfunkel, with the latter's acoustic "The Sounds of Silence" being remixed with rock instruments to be the first of many hits. Folk rock reached its peak of commercial popularity in the period 1967-8, before many acts moved off in a variety of directions, including Dylan and the Byrds, who began to develop country rock. However, the hybridization of folk and rock has been seen as having a major influence on the development of rock music, bringing in elements of psychedelia, and helping to develop the ideas of the singer-songwriter, the protest song and concepts of "authenticity". Psychedelic rock Psychedelic music's LSD-inspired vibe began in the folk scene, with the New York-based Holy Modal Rounders using the term in their 1964 recording of "Hesitation Blues". The first group to advertise themselves as psychedelic rock were the 13th Floor Elevators from Texas, at the end of 1965; producing an album that made their direction clear, with The Psychedelic Sounds of the 13th Floor Elevators the following year. Psychedelic rock particularly took off in California's emerging music scene as groups followed the Byrds from folk to folk rock from 1965. The psychedelic life style had already developed in San Francisco and particularly prominent products of the scene were The Grateful Dead, Country Joe and the Fish, The Great Society and Jefferson Airplane. The Byrds rapidly progressed from purely folk rock in 1966 with their single "Eight Miles High", widely taken to be a reference to drug use. Psychedelic rock reached its apogee in the last years of the decade. The Summer of Love of 1967 was prefaced by the Human Be-In event and reached its peak at the Monterey Pop Festival, the latter helping to make a major American star of Jimi Hendrix. Key recordings included Jefferson Airplane's