1. Researchers used a metacontrast masking paradigm to create conditions in which the subjective report of consciousness differed but the objectively measured ability to discriminate visual targets did not, allowing them to study the neural correlate of consciousness while having performance levels carefully matched in healthy human subjects.
2. A comparison of the neural activity associated with these conditions as measured by functional MRI showed that conscious perception is associated with spatially specific activity in the mid-dorsolateral prefrontal cortex (area 46).
3. The results suggest that the prefrontal cortex is important for the essentially subjective aspects of conscious perception and that relative blindsight can be used as an approach to study visual consciousness in normal human subjects.
The article "Relative blindsight in normal observers and the neural correlate of visual consciousness" presents a study that aims to uncover the neural correlates of visual consciousness by creating experimental conditions in which subjective reports of consciousness differ while objective measures of discrimination ability remain constant. The study uses a metacontrast masking paradigm to create two conditions with matched performance levels but different levels of subjective awareness. The results show that conscious perception is associated with spatially specific activity in the mid-dorsolateral prefrontal cortex (area 46).
Overall, the article presents a well-designed study with clear methods and results. However, there are some potential biases and limitations to consider. One limitation is that the sample size is relatively small, with only 13 participants included in the fMRI study. This may limit the generalizability of the findings and increase the risk of Type II errors.
Another potential bias is that the study focuses on healthy human subjects rather than individuals with visual impairments or neurological disorders. While this approach allows for more precise control over experimental conditions, it may not fully capture the complexity of visual consciousness in real-world situations.
Additionally, while the study provides evidence for a neural correlate of visual consciousness, it does not address broader philosophical questions about what constitutes consciousness or how it arises from neural activity. The article also does not explore alternative explanations for the observed activation in area 46, such as its role in attention or working memory.
Finally, while the article notes that blindsight has been controversial and difficult to replicate in some cases, it does not fully acknowledge these challenges or potential limitations to using blindsight as a model for studying visual consciousness.
In conclusion, while this article presents an interesting and well-executed study on relative blindsight and its neural correlates, there are potential biases and limitations to consider when interpreting its findings. Further research is needed to fully understand the complex nature of visual consciousness and its underlying neural mechanisms.