Our brain is designed to quickly detect things that may be important for our survival, such as potential threats or pleasant stimuli. However, in everyday life, many visual signals appear under difficult conditions: in low light, fog, shadows, or with low visual contrast. Does the brain continue to prioritize emotional information when we can barely perceive it?
PhD student Germán Cipriani, from the Mind, Brain, and Behavior Research Center (CIMCYC) at the University of Granada, together with researchers from the CEACO group at the Autonomous University of Madrid, led by Dr. Luis Carretié, have studied how emotional images capture attention even when they are very difficult to see.
In the study, volunteers performed a simple perceptual task while being shown images with negative, neutral, or positive content in the background (e.g., threatening or pleasant scenes). These images were displayed at different levels of contrast, including an extremely low condition in which they could not be consciously recognized. During the task, brain activity was recorded using electroencephalography (EEG), a technique that allows to record how the brain responds to stimuli with high temporal precision.
The results showed that, even when the images were almost invisible, the brain still reacted differently depending on their emotional content. In the first few tenths of a second after the stimulus appeared, negative images generated a stronger brain response than positive ones. This pattern suggests a bias toward the negative, probably related to the evolutionary importance of quickly detecting threats.
In later stages of brain processing, positive images elicited a greater response than negative and neutral images. This effect could reflect a complementary tendency of the brain: in addition to identifying dangers, we also prioritize pleasant stimuli that encourage exploration and approach.
Although no significant differences were observed between the different types of emotion in behavioral measures, there was a general effect of worse and slower task performance when the images were more visible. This indicates that the brain can automatically prioritize visual distractors and that the visibility of the stimulus modulates its impact on performance.
Taken together, these findings suggest that the human visual and attentional system is highly efficient: it can detect and prioritize emotionally relevant stimuli even when visual information is very limited or barely conscious. This rapid and automatic processing could be an evolutionary adaptation to react quickly to threats and, later, to desirable opportunities in complex and changing environments.
Understanding how the brain processes emotional information under conditions of limited perception can help explain everyday phenomena, such as the intuitive detection of danger in the dark or the automatic attraction to positive stimuli. Furthermore, this knowledge can be useful for understanding alterations in attention to emotional stimuli in psychological and neurological disorders.
Reference
Cipriani, G. A., Kessel, D., Álvarez, F., Fernández-Folgueiras, U., Tapia, M., & Carretié, L. (2025). Emotional distractors modulate event-related potentials even at very low contrast levels. Cortex, 189, 191–204. https://doi.org/10.1016/j.cortex.2025.05.018
Contact at the CIMCYC
Germán A. Cipriani (gcipriani@ugr.es)