December 2011 - Issue #14
Instant perception a visionary marvel
Story by Gio Braidotti
View articles in related topics: Design, Film, Multimedia, Health & Medical, Society
Key points
- Research at Swinburne has found that people are able to consciously perceive images even if displayed for as briefly as 1/1000 of a second.
- The research has cast new light on so-called subliminal vision.
Developed in the 1960s, the ‘subliminal effect’ is the idea that rapidly flashed images may influence behaviour, despite the images not being consciously perceived. In its day the hypothesis, with its undertones of mind control, fuelled Cold War paranoia and today continues to pique public imagination through the way it could be used by advertisers.
However, a Swinburne University of Technology study has upturned previous research on visual perception. Its new findings show that human brains can consciously process visual information so fast as to stretch the limits of modern measuring instruments.
The unexpected result has far-reaching implications in psychology, including evolutionary explanations for uniquely human vision attributes, and spells the end for ideas of mind control via the subliminal effect.
New devices, deeper perception
The visual perception project is the brainchild of Professor Allan Whitfield, director of Swinburne’s National Institute for Design Research. He says that early in the project a technical flaw was discovered in instruments previously used for subliminal research, sidetracking the project into the invention of a new way to display images rapidly.
The task fell to the institute’s Dr Clementine Thurgood and Associate Professor John Patterson of Swinburne’s Biomedical Group.
Associate Professor Patterson explains that past technical problems were due to limitations in display hardware. While it is relatively simple to produce an extremely rapid flash of light, presenting a complex visual image rapidly is much more difficult.
“For our study, we loaded a digital image onto a dark liquid crystal display (LCD),” he says. “When the image was fully loaded we backlit the screen with a single flash from an array of light-emitting diodes (LEDs) that reach full luminance almost instantly. That is what allowed us to control the visible duration of the image.”
Called an LED-tachistoscope, and now patented by Swinburne, the instrument can display images as briefly as a millisecond (ms), 1/1000 of a second. For comparison, 3/1000 is the duration of a housefly’s wing flap. Such rapid exposure times were confirmed using a photodiode – a transistor that only conducts electricity when exposed to light.
“We did not seriously expect people to recognise an image when exposure was less than 10 milliseconds,” Dr Thurgood says. “So we were stunned when John – the first person tested – clearly recognised the image of a dog, including the breed, after a one millisecond exposure.”
Rapid minds respond faster
During the subsequent study, humans proved 90 per cent accurate at recognising images of animals displayed at one and 10 milliseconds. “All reported consciously seeing the images,” Dr Thurgood says.
Associate Professor Patterson recalls being “flummoxed” by the outcome. “As a physiologist, I did not believe humans were that fast. For me, the result has precipitated a reappraisal of visual perception theory.”
Professor Whitfield now doubts that there is any such thing as a subliminal effect. Instead, he is using LED-tachistoscope technology to study attributes of visual perception more broadly.
With no speed limit yet detected, the Swinburne team has built a second-generation LED-tachistoscope to further reduce exposure times to less than 1/1000 of a second. Preparations are also underway to measure electrical brain activity during rapid perceptions using electroencephalography (EEG).
Spotlight on the discerning eye
Several new research projects relying on the new technology are now underway. Of interest to Dr Thurgood are processing rates for emotions associated with visual perceptions. She is working with Professor Gitte Lindgaard of Carleton University in Ottawa, Canada (soon to join the team at Swinburne), to examine the minimal stimulus input needed to evaluate the visual appeal of web pages.
Then there is work on the ‘mere-exposure effect’, in which repeated exposure to an image is found to increase its appeal. “It sounds unbelievable, but it works,” Professor Whitfield says. “My interest in these effects is that they involve an area of psychology to do with understanding aesthetics.”
While not immediately obvious, aesthetics actually link with human visual perceptions to an extraordinary extent. Professor Whitfield points to the billions of dollars spent on beauty products and fashion, through to the use of decorative design and colours even of utilitarian objects such as bicycles, garden tools and water bottles.
“We control the appearance of more and more things, especially as we get richer,” he says. “Yet despite its incredible influence, aesthetics is taken for granted and is poorly understood. That is what I want to reverse.”
Beginnings of an experimental career
Originally aiming for a career in clinical psychology, Dr Clementine Thurgood studied psychology and psychophysiology at Swinburne, only to opt for research at the last hurdle.
The turning point came in 2005 after she completed honours at Swinburne’s Brain Sciences Institute and realised the vastly greater learning opportunities associated with research.
Recruited to do a PhD in the Faculty of Design by Professor Allan Whitfield, Dr Thurgood undertook a series of exceptional experiments that proved humans are able to consciously process visual stimuli at exposure durations far faster than previously measurable by equipment.
Her doctoral studies hinged on resolving the technical issues of presenting complex images at very short time intervals and in the process she joined in the invention of the LED-tachistoscope.
“It is letting us do new things and I am quite happy to be involved, exploring different research areas and seeing where the data takes us,” she says.
Her curiosity-driven journey will include a year in the Netherlands working with collaborators at the Delft University of Technology as part of an international collaboration to, once again, attempt the unprecedented. In this case, it will be to help model the psychology that underlies the quintessentially human perception of aesthetics.
