Birthday, painted in 1942, depicts Tanning standing in a room, holding open a door. Behind her, doors stretch endlessly, each open door leading to another. The use of diagonals with the positions of the doors and the slant of the plank wood floors creates a disorienting scene and allows the viewer to resonate with the bewilderment seen on Tanning’s face. On the floor before her, a furry, winged, lemur-like creature crouches, claws digging into the hardwood floor. Tanning herself is dressed in a strange outfit, consisting of a seaweed-like coat, a draping of gray cloth as a skirt, and puffy sleeves of rich purple and gold edged in lace. Her breasts and stomach are exposed, and she holds the gray cloth over her lower body. She stares just past the viewer, in a frozen position, as if she had suddenly stopped walking. Her hand is on the knob of a door, one bare foot in front of the other, left shoulder forward. Despite her confused and forlorn expression, her body language is strong, stomach lean and muscular, left hand confidently covering her lower body.
Perhaps one of the most compelling aspects of this piece are the endless doors behind Tanning. There are eight visible doors, although more are implied as they fade into the vanishing point. This creates a dizzying infinity mirror effect and draws the viewer into the painting. Open doors are a motif seen time and time again in Tanning’s works. They are meant to represent infinity and perspective, as stated in her 2001 autobiography, Between Lives; An Artist and Her World.
“We scoff at perspectives which are, after all, so false: the endless stairs, the unscalable walls, even the doors that I had painted, half open like Venus’s flytraps irresistible snares inviting me in. Yes, I had painted them as if doing so would liberate me from a doom of perspective, the beckoning nowhere that had dogged my errant life so far” 
Maternity, 1946-47, is composed of a woman holding a baby, both swathed in white cloth, standing between two doors. The door in the background is open, and there is a white figure standing behind it. It is unclear if the door closest to the woman is open or closed. Bon Soir (Good Evening) , painted in 1951, is an oil painting featuring a shadow figure opening one door to reveal a second door behind it. Intérieur (Interior) , 1953, depicts a distressed child straining to push a door closed against a disturbing creature made of cloth and flesh, with several other open doors in the back and foreground.
Tanning also discusses the doors in Birthday, and her inspiration for incorporating them into the background of the painting.
While Tanning does attempt to describe this motif, she does not do so directly, leaving the doors shrouded in mystery. An exhibition guide, for the Tanning exhibit in the Tate Modern, suggests that the doors are “ a portal to the unconscious.”  A focus on the unconscious is not uncommon in surrealist works, as many of the works from this period depict strange dreamscapes and depict complicated emotional meaning.
“I had been struck, one day, by a fascinating array of doors—hall, kitchen, bathroom, studio—crowded together, soliciting my attention with their antic planes, light, shadows, imminent openings and shutterings. From there it was an easy leap to a dream of countless doors. Oh, there was perspective, trapped in my own room!” 
If the doors are meant to represent the unfolding of the unconscious, then the figure of Tanning seems to be holding these doors open. Her body language is rigid and strong, yet she’s poised on the balls of her feet as if she’s prepared to flee at any moment. The way she looks at the viewer suggests an air of intrusion. As Alice Spawls writes, “we are witnessing a woman on the verge of some transgression—or protecting herself from one.”  It is as if she is challenging the viewer, demanding an answer for why they are there, looking at her. The viewer is intruding upon a private moment, and yet they can’t look away.
As an artist, one is called to lay their private feelings and lives bare in their artwork, for others to view and ruminate on. There is an invasion of privacy in displaying artwork, even more so in a self-portrait, as the artist quite literally paints themselves into the piece. They are telling viewers who they are, revealing a primal part of themselves. Tanning seems to recognize this, as her wide eyes and slightly raised brows communicate fear or apprehension. However, her jaw is set and her lips are tight; she is both a guard and a host to the unfolding doors of her unconscious.
This creates an interesting line of communication between the artist and her audience, a willingness to be vulnerable for the sake of self-discovery. There is a simultaneous push and pull effect; the doors draw the viewer in, then spits them back out, leaving them just as confused as Tanning, but perhaps not as strong. She presents a challenge to the viewers as she faces her unconscious and the things she does not understand.