We can do irony for you wholesale: Philip K Dick's head is missing. Not the head the late science fiction writer was buried with, but part of an automaton that sat in a living room set interactively conversing with visitors. Before the loss, there were thoughts that the head might help promote the current movie A Scanner Darkly, based on Dick's 1977 novel. No such luck.

When last seen, the head was bagged face-down in a chunk of foam and placed in an overhead bin on an America West flight home to Las Vegas, after being demonstrated at Google. Its creator, David Hanson, was so fried from overwork and overtravel he left the plane without it. Do lost robot heads dream of Isaac Asimov?

"I have a lot of dreams, but I cannot remember them all," the PKDbot says in a video clip on co-creator Andrew Olney's website (http://tinyurl.com/okbvh). The head looks remarkably lifelike (except for the electronics visible at the back of its head), but its voice, while retaining qualities of Dick's own voice, has unmistakably synthesised rhythm and tone.

Copyright violation

The author behind Bladerunner (1982), Total Recall (1990), Minority Report (2002) and Paycheck (2003) was a logical subject for a "robotic portrait." He loved to play with reality and existentially challenged robots, and even in the 1950s was so prescient that the mainstream is still catching up. In A Scanner Darkly - the novel and film - the federal anti-drug counter-counter-surveillance is so recursive that the hero is assigned to spy on himself.

Olney's basic strategy for creating the brain was that sketched in Dick's 1972 novel, We Can Build You, in which a couple of failing electronic organ salesmen in Boise, Idaho, build a simulacrum of Edwin M Stanton, Abraham Lincoln's Secretary of War. The Stanton can not only talk and respond, but learn, adapting quickly to life in 1981. It even ponders setting up its own law practice, especially after they create a second simulacrum, of Lincoln himself.

Olney had approximately 20 of Dick's novels scanned in, along with interviews, speeches and details about Dick's life. The resulting mass of text was formatted and fed to algorithms for latent semantic analysis, a mathematical technique that makes it possible to index, retrieve, and extract meaning from natural language. Most software he used is open source. The robot's sound comes through a speaker in its chest (there wasn't room in the head), and the face lip-synchs.

"It's like a kind of [ventriloquist's] dummy," says Olney. "It's the computer or laptop brain [wired to the robot] that's really smart." A copy of that brain survives on Olney's laptop.

Technically speaking, scanning in the novels was a violation of copyright. Olney says they didn't exactly have the Dick estate's permission, but "we very much wanted their goodwill", and he felt the PKDbot was "fair use". He notes that they made no profit from the project.

The problem of intellectual property rights is one of the few aspects of modern life (other than the vastly changed role of women) that Dick didn't foresee. Is an automaton a portrait? Or is it a copy? A derivative work? Or perhaps a recording?

In the mid-1990s, a chain of bars operated by Host International copied the setting of the TV series Cheers and included animatronic figures ("Hank" and "Bob") evoking Cliff, the postman (played in the series by actor John Ratzenberger), and the portly barfly, Norm (George Wendt). Witnesses say the robots resembled stuffed dolls that moved a bit and traded pre-recorded jokes. Paramount, which owned the series, granted the bars - and characters - a licence as "derivative works", taking the view that it owned all rights. Ratzenberger and Wendt didn't; they sued Host for unfair competition and violating their "right of publicity".

The precedent: Wheel of Fortune vowel seller Vanna White had sued Samsung for running full-page magazine ads featuring a picture of a White-alike robot (tinyurl.com/goy8m). White won $403,000 and a judgement that California's right of publicity was not limited to name, likeness, voice, or signature. In the contest between US federal copyright law and California state law, Wendt and Ratzenberger won.

Judge Alex Kozinski wrote eloquent dissents in both cases, arguing that instead of preventing the "evisceration" of White's rights (as White's side argued), the court was "creating a new and much broader property right".

In the UK, says Lilian Edwards, professor of internet law at the University of Southampton and part of a project to create a database of personality law, no such personality or publicity right exists. In some circumstances a live person might be able to sue for defamation if the representation was "lowering his reputation in the eyes of right-minded people". But not a dead one. Nonetheless, California sets the pace in this area.

Creativity and compassion

But the PKDbot can't infringe any rights anywhere, because it remains headless. It bugs Olney that the loss has overshadowed their technical and artistic achievement. The PKDbot was far less sophisticated than the robots Dick imagined in his work - for example, the android in The Electric Ant, who believes he is human until hospital doctors tell him otherwise. (Inside his chest he finds moving reels of punched paper tape; when he reconfigures the holes, reality shifts.)

But it was certainly more automatous than John Edward Yancy, the beloved, fake, mind-controlling planetary guru used to create a peaceful totalitarian society in The Mold of Yancy (1955). Yancy rolls on "confident, amiable, undisturbed" until it freezes, fresh out of programmed words and gestures.

Strategically placed microphones meant the PKDbot could hear questions; responses came after a computational delay of varying length depending on the complexity of the question. Cameras, sensors and machine vision meant it could look you in the eye and even recognise a few friends and Wired editors.

"We tried to make it move the way Dick did in the movie we had, and also tried to make the voice a reasonable match," Olney says. "If you take all those things and bring them together, you've taken the idea of a portrait and pushed it into several dimensions you don't normally see."

He believes the way the two brought the portrait together represented a big advance over other automata, which he describes as mostly pneumatic, not very portable, and limited in what they can say. "Really, this robot was wide open. You might not get the response you wanted, but it was a representation of Philip K Dick."

In the video clip, the PKDbot seems as uncertain of its reality as any of Dick's characters. If it is asked, "When were you born?" then it answers alternately, "I was activated ..." and "Phil was born ..." Both versions lead to December 16, 1928, in Chicago, Dick's date and city of birth.

The Stanton's creators wanted to mass-market simulacra to teach, take care of children, and re-enact the US civil war (with the purpose of ending all other wars). But Seattle-based Sam K Barrows - America's youngest, richest billionaire, who makes his money speculating on extraterrestrial land - wants to buy up the technology so he can make his colonies less lonely. Today, in Japan, robot makers hope robots can care for the elderly.

At first thought, automata ought to be more acceptable as entertainment than as carers. And yet, Olney says that at shows where the PKDbot was set up: "A lot of people would come up and hold the robot's hand, though they weren't really invited to do that. It was very interesting to me that by making it look very human and respond as humanly as we could, it could evoke that kind of response. It says something about human psychology."

Plus, if you're holding its hands, you know it can't reprogram its inner reality tapes and wink you out of existence.

· If you'd like to comment on any aspect of Technology Guardian, send your emails to tech@theguardian.com