Cancer symptoms often go undetected in CAT scans and x-rays

People who interpret x-rays or CAT scans often fail to notice symptoms of diseases such as brain cancer or breast cancer. This emerged from a new research study led by Árni Kristjánsson, professor of psychology at the University of Iceland, along with Mauro Manassi and David Whitney at the University of California, Berkeley. The findings appear in the journal Scientific Reports, published by Nature this week. Their research shows how systematic errors of perception can occur in people who regularly examine x-rays, e.g. due to suspected cancer of various kinds. The scientists have their own ideas about how to improve procedures for such visual searches. Going by their findings, it is clear that this research is incredibly useful and Árni believes that with the right response, it could potentially save lives. "In our research, we consider whether there is anything in the process of visual perception itself that could explain human error. We have previously confirmed that what people have already seen can skew their perception of what they see afterwards, a so-called serial dependence in perception," says Árni Kristjánsson, whose career has mainly focused on understanding the human visual system and how attention and visual perception work together.

"We designed a separate visual perception study as part of our research, containing elements that resembled signs of cell changes in x-rays. We did this to measure whether and how serial dependence can affect the way people perceive stimuli and whether this could change people's perceptions and even cause errors."

Árni says that the research furthermore shows that the less common the stimuli, the more likely it is that participants will fail to find them in the images they view.

The same factors could affect security guards in airports

Árni says that the findings definitively show that serial dependence can impair people's perception of stimuli that resemble x-rays, thereby directly affecting the results of examinations. "We also tried to answer the question of whether stimuli of this kind could affect the perceptions of people searching for weapons and other dangerous items at airports."

He says that unfortunately, it is very common for x-rays and CAT scans to be misinterpreted. "Studies suggest that around 20% of cases go undetected in images taken due to suspected breast cancer. It is also common for dangerous objects to make it through security scans at airports."

Many reasons for human error

Árni says that his and his colleagues' research has focused on how and why people make these kinds of errors. "This study indicates one important reason for human oversight. Since we have now demonstrated this human weakness through research, it is natural to start thinking about measures to remedy it."

Árni says that there are many reasons that people perceive things incorrectly. "Serial dependence could be one of these reasons, meaning that our perception of reality is shaped by previous experience. In my opinion, the remedy is clear and first and foremost involves breaking up the serial dependence, by using various different methods to investigate such stimuli, for example by changing the perspective. Increased variability in the way stimuli are investigated could help, as well as giving people regular breaks from this kind of work."

Importance of basic research

Árni says that basic research such as this, focusing first and foremost on understanding the basic process of perception, is absolutely vital.  "In order to use research to improve quality of life, health, etc, basic research is necessary. It is worrying that governments demonstrate such little understanding of this. It is important that decisions we make about our society are based on good quality data. The reliability of scientific findings plays a key role here."

A talented scientist and entrepreneur

Since 2004, Árni Kristjánsson has been an academic member of staff at the University of Iceland, working on diverse research projects in the field of psychology. For example, he has researched the functionality of visual perception in people with anxiety disorders and dyslexia.

Árni has also attracted a lot of attention for multidisciplinary research that has led to innovation; he is one of Iceland's representatives on the Sound of Vision project, led by scientists at the University of Iceland. The project last year won the "Tech for Society" award at ICT, an EU research and innovation event. The project aims to develop a high-tech sensor device that will help visually impaired people get around without the need for other aids.