Answer:
perceptual screen
Explanation:
According to my research on studies conducted by various psychologists, I can say that based on the information provided within the question Carl has most likely created a perceptual screen to shield him from all the competing messages. This term refers to a psychological window through which we interact with people that influences the quality, accuracy and clarity of the communication. Which seems to be the case with Carl, and why he no longer notices new groups or signs.
I hope this answered your question. If you have any more questions feel free to ask away at Brainly.