Reading Steiner is a term coined by Okabe, referring to his unique ability of retaining memory of events as they occurred before the switch after switching world lines,
Okabe would eventually discover that everyone has Reading Steiner in some capacity, though he would remain the sole character in the series who is shown to have Reading Steiner strong enough to retain all of his memories following a world line shift.
In many Beta world lines, the general population unknowingly experiences notable Reading Steiner. In 1.382733β, this ability is referred to as President's Disease, as those with this ability remember Puchin as the President of Russia instead of General Secretary of the Soviet Union. In other world lines of the Beta Attractor Field, Reading Steiner is minimal and treated as a new form of encephalitis.
The ability plays a major role in the plot, most prominently in allowing Rintaro to undo the changes caused by the D-Mails and not losing track after each switch.
In the anime, there is a visual distortion every time Reading Steiner is activated, often following the sending of a D-mail.
Other relevant characters have been known to experience stronger forms of Reading Steiner due to Okabe's involvement. As a result of some sort of reflection, they seem to regain fragments of these memories occasionally.
- In 0.409431α, Faris remembers her D-Mail from 0.456903α that prevented her father's death and transformed Akihabara after escaping the Viral Attackers, after being talked through events with Okabe's assistance,
- in 0.456914α, Lukako remembers her first meetings with Okabe in various other worldlines as a male, after Okabe assists by prompting a discussion surrounding their meeting.
- In 0.571046α, Mayuri visits her grandmother's grave, explaining to her granny that she remembers "nightmares" in which she dies in a multitude of ways. Her Reading Steiner is depicted as strong as she is able to remember these events without Okabe's assistance, rather her recollection comes from his involvement in trying to prevent said deaths.
- In 1.129848β, Katsumi Nakase is able to vaguely recall Mayuri's death from various world lines as a "dream" of sorts. Her Reading Steiner is depicted to be strong as she recalls these events without Okabe's assistance, rather her recollection comes from Okabe in these iterations prompting reflection in the form of a short-lived hypothetical.
- In 1.048596%, or the "Steins Gate" world line, Kurisu instinctively recalls Alpha worldline memories midway through an interaction with Okabe, bewildering even herself mere seconds later.