Weak brain stimulation to the forehead reduces objectification bias in recognizing sexualised images

Overview

The Conversation reports on a study exploring whether a brief, mild electrical stimulation of the forehead can affect how people perceive sexualised images of women compared with men.

• The researchers used a Thatcher illusion inspired task to test recognition of photos of models in underwear, upright or upside down.
• In a double-blind, placebo-controlled design, participants were split into a stimulated group and a placebo group.
• In the placebo group, men were remembered better when images were upright, while women showed a smaller upright advantage, consistent with objectification biases.
• In the stimulation group, upright recognition of images of women improved and the gender gap closed, while recognition of men’s images remained unchanged.

Author: The Conversation

Introduction and background

Memory studies have long shown that people tend to recognize faces and bodies more accurately when they are oriented upright, a pattern known as the upright advantage. Previous work suggested that sexually objectified images of women can distort perception, making it harder to remember individual identity compared with sexualised images of men. The Conversation reports on a new experiment that tests whether a mild, noninvasive brain stimulation technique can temporarily modulate this bias and thus alter perception in the moment.

The Thatcher illusion and the memory task

The authors connect the current work to the Thatcher illusion, a famous visual illusion where a face with upside-down features can appear grotesque when upright but looks nearly normal when inverted. Prior research showed Thatcherised faces disrupt recognition less than normal faces, hinting that high-level configurations can be taxed by attention to shared facial features. The researchers hypothesized that sexualised bodies in images may generate a similar pull, crowding out the details that distinguish individuals from one another. To test this, 76 university students memorised photos of male and female models in underwear, with half the images shown upside down and the rest upright. A subsequent recognition test mixed original photos with new ones, and participants indicated whether each image had been seen before.

Methods: stimulation vs placebo

Participants were randomly assigned to receive a weak transcranial direct current stimulation (tDCS) to the forehead for ten minutes or a placebo that simulated the sensation but delivered no sustained current. Neither the participants nor the researchers assessing them knew which condition was active, ensuring a double-blind design. The stimulation targeted regions implicated in visual processing and learning to see, with the aim of reducing the crowding effect of shared body features on recognition.

Findings: effect on women and men

In the placebo group, the usual upright advantage persisted for men, who were remembered more accurately when their images were upright than upside down. For women, the upright advantage was much smaller, driven by poorer memory for upright images of women relative to upright images of men. In the stimulated group, the recognition of upright images of women improved, and the gap between men and women disappeared. The upright advantage for images of men did not change with stimulation, indicating a gender-specific modulation rather than a global shift in perception.

Interpretation: a learning-to-see mechanism

The authors interpret these results through a theory of how people learn to see. With experience, the brain learns to downplay features common to many faces and bodies and to focus on idiosyncratic details that differentiate individuals. However, certain shared features in sexualised images—such as exposed body parts—tend to grab attention, crowding out those distinctive details. The mild electrical current to the forehead may attenuate this pull, enabling more successful encoding of unique features for upright images of women.

Limitations and caveats

The study was conducted in a single lab session with university students and measured only immediate memory effects, not attitudes or behaviour. Since every image used was sexualised, the researchers cannot separate the biases arising from sexualisation per se from other image differences. The authors caution that brain stimulation is not a cure for sexism; the effect is temporary, and broader cultural and behavioural factors remain central.

Implications and broader context

Despite limitations, the work suggests objectification may reflect habitual visual processing that can be temporarily shifted by noninvasive brain stimulation or even by tasks that engage power dynamics, as discussed elsewhere in the article. The overarching message is that objectification could be a modifiable habit rather than a fixed property of the human perceptual system, with implications for how we study and address bias in everyday life.

Concluding thoughts

While the findings do not argue for a general solution to bias or sexism, they open a line of inquiry into how perception can be nudged in the short term. The research underscores the idea that habits influence how we see others, and that small, targeted interventions may shift perception temporarily, revealing the plasticity of social vision.