Robin Dunbar remembers having his mind blown

SUMMER OF LOVE: ART OF THE PSYCHEDELIC ERA. Tate Liverpool until September 25 I hadn't realised that I could be part of history so soon.

Though, come to think of it, it was 40 years ago. The US phase of the Vietnam War had just started; the recently ex-professored Timothy Leary had acquired a certain notoriety with an obscure chemical originally developed by the Swiss drug giant Sandoz as a possible treatment for schizophrenia; I had just taken my A levels.

Then came Allen Ginsberg at the Albert Hall; "Granny Takes a Trip" - the first of the famous Sixties boutiques in Kings Road, Chelsea; London's first underground newspaper, IT; Ravi Shankar; the Maharishi; The Beatles'

Sgt Pepper's Lonely Hearts Club Band ; Procol Harum's Whiter Shade of Pale - and suddenly it was all happening. We were carried along on a surging, swirling tide of psychedelia, blue smoke and jumbled words that we mistook to have deeply philosophical meaning.

Revisiting all this in the Summer of Love exhibition at the Tate Liverpool - the best I have been to here in nearly two decades - is a kind of reminiscence therapy for those of us of a certain age. For one thing, I hadn't realised just how brief the psychedelic art period had been - by 1969, it was all but over, with Glam Rock and the androgynous look just around the corner.

But here - in a cascading torrent of album covers, period photographs, artwork, billboard posters, be-in experiences, original light shows, Janis Joplin's pristine-condition psychedelic 1965 Porsche 356C sports car, copies of assorted British and American underground newspapers, and the infamous "Turn on, Tune in, Drop Dead" cover of issue No 77 of MAD magazine - is all the weird and the wonderful that kept me from lectures through my years at university.

With the benefit of hindsight, one forgets how crude the technology was.

Experimental film clips of kaleidoscopic effects and super-imposed images blew one's mind at the time, but now they seem laboured. Here is the original photomontage of OZ's 1967 "Plant a Flower Child" poster by Martin Sharp and Robert Whitaker, its hundreds of cut-out pictures of the same naked model that had been laboriously pasted together now curling at the edges.

I suppose that I hadn't really appreciated - until I saw the photographs - that all those swirling light shows were done by hand using glass dishes filled with oils and water placed on banks of overhead projectors. What then took six or seven people a lot of time and effort on the night can now be put together in a matter of minutes by a 14-year-old playing on a computer. But some of it was just plain clever. There is Lee Conklin's 1968 poster for a Paul Butterfield Blues Band performance with its image of a humanoid composed entirely of hands. The swirling Pre-Raphaelite-esque posters of the London-based Hapshash & the Coloured Coat design team. And Private Eye 's innocently mischievous observation that, according to the Queen, Prince Philip went on a lot of trips during the Sixties.

Two curious details of purely academic interest caught my eye. One was a 1969 Bryan Wharton photograph of a very youthful Germaine Greer sprawling languidly with a surprisingly shy smile. The other was a letter from Francis Crick, the discoverer of the double-helix structure of DNA, explaining that he had just enjoyed pot during a recent visit to the US and asking how he could get hold of some in Britain.

Robin Dunbar is British Academy research professor at Liverpool University.