Revisiting the Searchlight Hypothesis

Given the finite computational power of the brain, it must prioritize the most urgent information from its affective inputs. Using a systems biology approach, I propose that the reticular nucleus of the thalamus performs the function of a variable-threshold gate for all parallel streams of primary affective information, which allows the conscious mind to perform work on only the most urgent threats to survival at any given time. The threshold of such a thalamic gate would be dynamic, would correlate positively with a person’s overall level of stress, and would provide an unconscious, automatic mechanism for the resolution of intrapsychic conflicts. This suggests that the primary aim of development is not to learn how to resolve intrapsychic conflicts, but rather to learn a diverse set of strategies that are sufficient to respond to the needs of every primary affective system with a high level of certainty. I also extend ideas formulated in the Solms model to re-organize psychological defenses along a continuum of the mind’s perceived entropy of its most pressing current task. I combine this organization of psychological defenses with the variable-threshold thalamic gate hypothesis (1) to suggest that projective identification is not a singular defense, (2) to simplify the etiology of borderline personality disorder, and (3) to explain the success of psychodynamic psychotherapies that focus on conscious affect.