The phenomenon you are describing is known as "intrusive thoughts" or "thought insertion." It is a common experience and can be caused by various factors related to how our brains process information and the nature of our thoughts.
Here are some possible explanations for why you may feel like you said something out loud when you actually said it in your head:
Automaticity of thoughts: Sometimes, our thoughts flow rapidly and automatically in our minds. During such moments, the distinction between thoughts and spoken words may momentarily blur, leading to the feeling that we expressed the thought verbally.
Sensory vividness: When we think or imagine something vividly, it may activate similar neural pathways as speaking aloud, making it feel more real and causing us to question whether we vocalized the thought.
Attention and memory: If you were preoccupied or not fully attentive while thinking, your brain might not have registered the thought as being internal. Later on, you may recall the thought and mistakenly believe it was spoken aloud.
Anxiety or stress: Feelings of anxiety or stress can lead to cognitive distortions and heighten self-monitoring. This increased self-awareness might make you more prone to noticing or questioning your thoughts and actions.
Pattern recognition: Our brains are excellent at recognizing patterns, and when we think of common phrases or responses, the familiarity might trick us into feeling like we said them out loud.
Mental fatigue or distraction: When you are mentally fatigued or distracted, you might lose track of whether you articulated a thought or kept it internal.
It's crucial to remember that experiencing occasional intrusive thoughts or thought insertion is normal and does not necessarily indicate any underlying mental health issue. However, if you find that these experiences are distressing, becoming frequent, or significantly affecting your daily life, it might be helpful to discuss them with a mental health professional. They can provide insight, support, and strategies to manage intrusive thoughts effectively if needed.