Dynamic display

Also called Dynamic screen, Page-based display, Navigating display

Screens that change page when a cell is chosen. Thousands of words in reach, at the cost of a navigation path the person has to learn.

What it is

A dynamic display is a screen-based aid where selecting a cell can open another page. Tap "food" and the food page appears; tap "people" and there are the people. It is how every modern communication app works, and it is what lets a tablet hold thousands of words when the screen only shows forty at a time.

The paper equivalent is the communication book, where turning a page is the navigation. The alternative on a screen is a static display, a single page that never changes.

Who it can help

People who need more vocabulary than one page can hold, which is most people once they are past the beginning. People who can plan a route: "to say pizza I go to food, then to hot food". Text users, who need a keyboard, a prediction bar, phrases and a symbol page all in one device.

It costs cognitive and motor effort. Every word behind a folder takes two or three selections instead of one, and a person with slow access, a memory difficulty or a visual impairment pays that cost on every word. A poorly designed dynamic system, where the core words move from page to page, is one of the most common reasons a device gets abandoned.

How it works

The vocabulary is organised into a tree of pages, held in the device's page set. A home page holds the core and the folders; each folder is a page of fringe; deeper folders hold more specific words. Good design keeps the core words in the same position on every page and puts each frequently used word as few taps from home as possible. Depth is the enemy: a word three folders down is a word that rarely gets said.

Most apps also let a cell speak and jump at the same time, or jump back to home automatically after a selection. These settings decide how many taps a sentence costs, and a therapist will tune them.

Getting started

Count the taps. Pick ten things the person says most and work out how many selections each one takes on their current device. Anything over three is a candidate for moving closer to home. A personal vocabulary page of the person's own most-used words, one tap from home, fixes a lot.

Don't move the core. If you must change the page set, change the fringe pages and leave every core cell where it was.

Give the person time on the navigation without pressure: exploring pages is how a person learns where things are, and it is not "playing with the device".

Where to get help

A speech and language therapist, and for complex needs a specialised AAC service, will choose and set up a page set for the person. ACE Centre publishes independent comparisons of the main apps' page sets. The suppliers, Smartbox and Tobii Dynavox among them, run free training on their own software.