I’ve long been interested in the progression of rapid serial visual presentation (RSVP) to facilitate certain types of reading. RSVP was originally pursued as a technological solution to speed limits on reading imposed by eye movement. See, in addition to the time required for eye-to-brain processing of words during fixations, there’s also the time taken by saccade movements when your eyes jump from one spot in a text to another. You can only move your eyes so fast. This explains, in part, why you’ll eventually hit a ceiling with reading speed.
RSVP attempts to solve this by displaying words in quick succession, one or two at a time, flashed in a single space on the screen.
Because RSVP never requires more than 5-20 characters on screen at a time, it didn’t take long for researchers to recognize that RSVP is a perfect fit for mobile devices.
I’ve been looking for the perfect mobile reader for some time, and while I still haven’t found the One Reader, I have discovered some good tools. Here’s a quick review of the better RSVP reading apps for the iOS:
Gotham Reader
App: https://itunes.apple.com/us/app/gotham-reader/id420684476

Gotham Reader integrates with Google Reader to fetch the full text of articles you’re subscribed to through RSS or Atom. Gotham Reader can’t open files or clipboard text.
And while loading Gotham Reader is painfully slow to start (it can take several minutes to sync each time you open the app), the settings and performance in reading are good.
I really appreciated Gotham Reader’s synopsis screen, which shows the first line or two of the post, along with all pertinent metadata, and an estimated time to read at the current rate.
Curiously, Gotham Reader lets you choose 2, 3, or 4 words per screen–but not 1. Type size can be controlled, but color can not.

Interface controls were intuitive: tap the article to start playing, tap to stop, which provides additional options, including speed.
Gotham Reader lets you save articles to finish later, or to store in Instapaper. You can also share any article.
What’s missing are labels for the rate and range of the display speed (this is simply indicated by a bar).
All-in-all, Gotham Reader is a solid RSVP reader, and indeed the only real RSVP reader that deals with RSS feeds with any kind of completeness or efficiency.
Simian Speed Reader (Speed-R)
App: https://itunes.apple.com/us/app/simian-speed-reader/id296829522

Simian Speed Reader provides RSVP display of TXT files. That’s all. But that’s really not terrible, considering Project Gutenberg. Still, I’d hope for ePub or PDF at the very least.

Simian lets you choose between 1-4 words per screen, and lets you select the display speed between 30 and 600 words per minute. I think the display speed is based on 1 word per screen, not actually on a calculation of the number of words per minute.
Simian lets you choose font as well as font color and background.
The RSVP reading experience in Simian is fairly stable, but note that the text size changes to maximize the size of the words on the screen. This can be disconcerting, so be sure to change the type size in settings down to a comfortable and consistent size if this bothers you.
There is also currently a bug that fails to account for punctuation when counting words. So, three-word phrase like “James said, ‘I” will show if you have two words set as the default.
Interface controls were simple, but limited: a Pause/Play button at the bottom must be hit to stop (whereas you’d hope to simply tap the screen anywhere).
I really want to like Simian Speed Reader, but it comes with a fundamental flaw: There is no Cancel, Done or other method of exiting Settings. This means you have to get out of the app and reopen it to return to the files menu.
Thankfully, Simian remembers exactly where you left off for each file.
iRSVP
App: https://itunes.apple.com/us/app/irsvp/id523989697

iRSVP provides RSVP display for files in a variety of file formats: “TXT, EPUB, RTF, DOC, DOCX, and limited support for PAGES ’09 and PDFs”. But this is even cooler: iRSVP’s Manage Files menu lets you add directly from Project Gutenberg by browsing and adding files within the app. iRSVP also supports clipboard pasting.
iRSVP Preferences lets you choose text color and background, and adds the useful ability to control punctuation delay speeds.

In addition to Pause/Play controls at the bottom of the display, iRSVP adds Previous Word and Next Word to facilitate review.
When paused, iRSVP shows your progress through the document, and lets you adjust display speed.
Like Gotham Reader, iRSVP fails to label the rate and range of the display speed (this is simply indicated by a bar).
iRSVP does not let you choose number of words or characters to display. You’re stuck with 1 at a time. This is iRSVP’s fatal flaw, I think, and I’ll elaborate on this in summary below.
LazyEye
App: https://itunes.apple.com/us/app/lazyeye/id415180387

LazyEye is an RSVP display reader for text pasted in from the iOS clipboard. Though LazyEye provides links to several content providers (e.g. LongReads), you still have to deal with select, copy, paste.
LazyEye’s Settings lets you slow down or speed up for punctuation, short words, or long words, though these are simple binary settings.

Each time you enter LazyEye the app reloads the current clipboard, making it impossible to pick up where you left off.
Once inside a text, LazyEye’s interface controls were intuitive: tap the article to start playing, tap to stop, which provides additional options, including advance or retreat one sentence or one paragraph.
Speed is controlled as words per minute, from 30 – 200.
LazyEye does not let you choose number of words or characters to display. You’re stuck with 1 at a time.
The paid version, Power Reader, seems to only remove ads and up to 1000 WPM. But with the clipboard limitation, I don’t know why you would bother.
Discussion
There are some obvious gaps in each of the RSVP reader apps reviewed here:
None of the apps accepted files directly from other apps, though they easily could. Most did accept text from the clipboard.
None of the RSVP reader apps were smart enough to use an if/else calculation to determine number of words based on visible characters. RSVP reading is based on the understanding that your eyes have a limited acuity, and the maximum range of focus in any fixation point is probably counted in characters, not words. True focus is about 4-5 characters, and some have estimated that since fixations can be 20 characters in length, the optimal number of characters is somewhere in between. An RSVP reading app would presumably be able to process a word, and if the number of characters is less than some amount (say, 12), it checks the next word. And so on. If the combined character count is less than the threshold, the reader displays both words. Otherwise it displays the one word, and moves on, repeating this check.
Nor did any of the RSVP reader apps show passage context on pause. It makes sense to show the words around the current highlighted word, perhaps in gray rather than white/black to show space. This, along with previous/next word/sentence tools such as those in iRSVP and LazyEye, might help address RSVP-related reading issues, such as attentional blink and task switching costs.
Finally, none of the RSVP reader apps built in any kind of note taking tools. At a minimum it would be nice to add notes at any point along the “timeline” of reading , i.e. when paused.
Obviously I have my own list of must-haves and nice-to-haves in an RSVP reader. But I’m fairly pessimistic about future developments, wondering if RSVP isn’t doomed to be the Dvorak keyboard of reading: a great idea with passionate advocates, but one that just can’t swim into the mainstream. Let’s hope I’m proved wrong by future iterations to these apps, or newcomers to the field.
Summary
While RSVP seems a perfect fit for reading on a small screen, there’s no one great RSVP app for the iOS. Gotham Reader is the best app of the handful reviewed here, but it works only with RSS fed content. There’s no great option for reading files. Though Simian Speed Reader and iRSVP are the best options, both suffer from some fundamental flaws. LazyEye is not yet worth your time.