Taking a ride down the... uncanny valley

In aesthetics, the uncanny valley is a hypothesized relationship between the degree of an object's resemblance to an individual being and also the emotional response to such an object. Since the uncanny valley was first described around psychologists, a standard hypothesis developed to clarify it. Referred to as the mind-perception theory, it proposes that when people see a robot with human-like features, they automatically add a mind to it. As per this theory, growing sense that a machine appears to own a mind ends up in the creepy feeling.  "Valley" denotes a dip within the human observer's affinity for the replica, a relation that otherwise increases with the replica's human likeness.

Wang Shensheng, the 1st author of the new study, who did the works as a postgrad student at Emory University and recently received his PhD in psychology, said, "We found that the exact opposite is true. It's not the primary step of attributing a mind to an android but a successive step of dehumanizing it by subtracting the concept of it having a mind that ends up in the uncanny valley. Rather than just a one-shot process, it is a dynamic one."

In an experiment involving the human lookalike robot Repliee Q2, the uncovered robotic structure underneath Repliee, and the actual human who was the model for Repliee, the human lookalike triggered the highest level of mirror neuro activity. [Credit: Wikipedia}

The findings have implications for both the design of robots and for understanding how we perceive each other as humans. "At the core of this research is that the question of what we perceive once we check out a face," adds Philippe Rochat, Emory professor of psychology and senior author of the study. "It's probably one among the foremost important questions in psychology. the power to perceive the minds of others is the foundation of human relationships. " The research may help in unravelling the mechanisms involved in mind-blindness - not being able to differentiate between humans and machines - like in cases of utmost autism or some psychotic disorders, Rochat says. Co-authors of the study include Yuk Fai Cheong and Daniel Dilks, both associate professors of psychology at Emory.

Anthropomorphizing, or projecting human qualities onto objects, is common. "We often see faces during a cloud as an example," Wang says. "We also sometimes anthropomorphize machines that we're trying to know, like our cars or a computer."
Naming one's car or imagining that a cloud is an animated being, however, isn't normally related to an uncanny feeling, Wang notes. That led him to hypothesize that something aside from just anthropomorphizing may occur when viewing an android.

To straighten out the potential roles of mind-perception and dehumanization within the uncanny valley phenomenon the researchers conducted experiments focused on the temporal dynamics of this method. Participants were shown three forms of images -- human faces, mechanical-looking robot faces and android faces that closely resembled humans -- and asked to rate each for perceived animacy or "aliveness." The exposure times of the photographs were systematically manipulated, within milliseconds, because the participants rated their animacy.
The results showed that perceived animacy decreased significantly as a function of exposure time for android faces but not for mechanical-looking robot or human faces. And in android faces, the perceived animacy drops at between 100 and 500 milliseconds of viewing time. That timing is in line with previous research showing that individuals begin to tell apart between human and artificial faces around 400 milliseconds after stimulus onset.

The second set of experiments manipulated both the exposure time and also the amount of detail within the images, starting from a minimal sketch of the features to a completely blurred image. The results showed that removing details from the pictures of the android faces decreased the perceived animacy beside the perceived uncanniness.
"The whole process is complicated but it happens within the blink of an eye," Wang says. "Our results suggest that initially sight we anthropomorphize an android, but within milliseconds we detect deviations and dehumanize it. which drop by perceived animacy likely contributes to the uncanny feeling."

Thumbnail credit: Mathieu Persan

Reference: Shensheng Wang, Yuk F. Cheong, Daniel D. Dilks, Philippe Rochat- ‘The Uncanny Valley Phenomenon and the Temporal Dynamics of Face Animacy Perception.’ Perception, 2020; 030100662095261 DOI: 10.1177/0301006620952611