Chapitre 1b : Les biais cognitifs

Introduction to Cognitive Biases

Overview of Cognitive Bias

• The video introduces cognitive biases, emphasizing their role in reasoning and information processing.

• Cognitive bias is defined as a distortion in reasoning that affects how we perceive and prioritize information based on personal beliefs and perceptions.

• Common characteristics of cognitive biases include being involuntary, unconscious, systematic, predictable, identifiable, and often stereotyped.

Classification of Cognitive Biases

• There are approximately 250 recognized cognitive biases; however, no official list exists. A link to a comprehensive resource is provided in the video description.

• Cognitive biases are categorized into six main types: sensory-motor biases, attentional biases, memory-related biases, judgment biases, reasoning biases leading to paradoxes, and personality-related biases influenced by culture and social factors.

Examples of Common Cognitive Biases

Confirmation Bias

• The confirmation bias is highlighted as one of the most frequent and damaging cognitive biases in biological research.

• This bias leads individuals to focus only on evidence that supports their existing beliefs while ignoring contradictory evidence.

• An example from 1988 involves researchers led by Jacques Benveniste who published results suggesting a molecular effect without molecules due to high dilutions of anti-serum.

Experimental Findings

• In allergic reactions involving basophils (a type of white blood cell), antibodies bind to allergens causing degranulation (release of histamine).

• Benveniste's team conducted experiments with extreme dilutions (up to 1/10^120), which theoretically contained no active molecules but still showed unexpected results regarding basophil degranulation.

Controversy Surrounding Results

• The findings sparked interest due to potential implications for homeopathy but also led to significant controversy over scientific validity.

• An investigation revealed that researchers fell victim to confirmation bias by selectively reporting positive results while disregarding numerous unsuccessful trials.

Factors Influencing Confirmation Bias

Research Environment

• Several factors contribute to the prevalence of confirmation bias among researchers:

• The urgency for rapid publication can lead scientists to favor confirming results over thorough validation.

• Unexpected findings require more substantial proof which may skew interpretation towards favorable outcomes.

• A strong desire exists within the scientific community for theories that align with established knowledge.

Selection Bias in Clinical Research

Understanding Selection Bias

• The second example discussed is selection bias within clinical research when testing new medications on human subjects.

Methodology Implications

• Typically involves comparing two groups: one receiving treatment and another receiving a placebo.

• If patient selection varies significantly between groups (e.g., age or health status), it undermines comparability and can skew study outcomes.

Understanding Selection Bias and Cognitive Biases in Medicine

The Impact of Selection Bias

• Results from treatment cannot solely be attributed to medication; they may also be influenced by age, gender, or pre-existing health conditions. This phenomenon is known as selection bias.

• Gender bias is prevalent in medicine, where certain diseases are incorrectly perceived as predominantly male (e.g., cardiovascular diseases, autism), while others are labeled female (e.g., osteoporosis, depression).

• Such biases can lead to significant consequences like misdiagnosis and delays in treatment; for instance, myocardial infarction may be underdiagnosed or diagnosed late in women, resulting in higher mortality rates.

Understanding Cognitive Biases

• Cognitive biases and heuristics were initially described in psychology and economics concerning decision-making mechanisms among individuals.

• Decision-making is heavily influenced by external factors (like lack of data or cognitive load) and internal factors (such as emotions, stress, or fatigue). A cognitive bias does not inherently make a decision wrong; other factors contribute to errors.

• A cognitive bias leads to irrational decisions based on invalid or imperfect information derived from heuristics. While a cognitive bias itself isn't an error, it can result in errors.

Consequences of Cognitive Biases

• Certain biases—confirmation bias, selection bias, and gender bias—can significantly impact scientific reasoning and medical practice. These biases can have detrimental effects on decision-making processes within these fields.