David Gaines plays a man unable to perceive anything located to his left in Spooky Action Theater's "The Man Who." (DJ Corey Photography)

A man inadvertently shaves just half of his face, leaving the other half slathered with shaving cream: In many contexts, this slip-up might seem comic. But it’s a matter for wonder, not laughs, in Peter Brook and Marie-Hélène Estienne’s “The Man Who,” which has been mounted by Spooky Action Theater. Inspired by neurologist Oliver Sacks’s book “The Man Who Mistook His Wife for a Hat,” the play introduces us to individuals living with unusual medical conditions, many of which involve impaired perception. Although the symptoms appear debilitating, the play is neither gloomy nor pitying, but rather awe-struck, as though the dramatists were marveling at the complexity of the human brain and nervous system.

Originally staged in Paris in 1993, “The Man Who” is steady and interesting, if not entrancing, in its Spooky Action incarnation, which is directed by Richard Henrich and billed as a D.C. premiere. On a white-on-white set that evokes a hospital, four actors — David Gaines, Tuyet Thi Pham, Carlos Saldana and Eva Wilhelm — juggle the roles of doctors (in white coats) and patients (in rumpled casuals) in scenes that dovetail in fluid fashion. Meanwhile, shifting colored lighting helps drive home notions of disorientation and subjectivity. (Colin Dieck designed the lighting, and Giorgos Tsappas, the set. Elena Day is the show’s associate director.)

Among the sequences that linger in the mind is Gaines’s portrayal of a man who is unable to perceive anything located to his left. After an orderly lathers his face, the man shaves just the right side of it; when the doctors show him his image in a mirror, his bewildered expression is tinged with terror.

In another poignant scene, Saldana depicts a man who has a twitching tic: As this almost-stoic patient tells his doctor that he despairs of ever having a romantic relationship, the tic contorts his head and neck, interrupting his words.

If some of the anecdotes are affecting, others have a bracingly defamiliarizing effect, prompting you to think about abilities you yourself take for granted. For instance, in one scene, Wilhelm embodies a woman who cannot recognize common objects, despite being able to see them. She is mystified by a glove, although she describes the article in detail and peers into its interior. Only when a medical professional slides the glove onto her hand does she realize what she’s looking at.

The episode makes you ponder the miracle that is recognition, a phenomenon that most of us would be hard-pressed to explain, even though we depend on it every minute. At its best, “The Man Who” is a welcome invitation to contemplate such mysteries. Most of us do not mistake our loved ones for hats — and that is a blessing.

The Man Who, by Peter Brook and Marie-Hélène Estienne, inspired by Oliver Sacks’s “The Man Who Mistook His Wife for a Hat.” Directed by Richard Henrich; sound design, Gordon Nimmo-Smith; costumes, Kim Sammis; props, Elizabeth Long; original compositions, David Schulman. About 90 minutes. Tickets: $30-$40. Through June 4 at Spooky Action Theater at the Universalist National Memorial Church, 1810 16th St. NW. Call 202-248-0301 or visit spookyaction.org.