From entry recognition rather than recall in glossary Human Computer Interaction the Basics
Humans are often far better at recogniton (seeing or hearing something and knowing what it means) compared with recall (retrieving it directly from memory). Interaction techniques that rely on recognition rather than recall tend to be easier to learn and easier to use. Many graphical interaction techniques (GUI) use this principle with actions and objects available through icons or menus. In contrast, a simple command line interface (CLI) requires that you know the names of commands.
There are ways to bridge this gap, for example, most conversational interfaces have relaxed grammar that does not require you to use an exact phrase or word. Also command line interfaces can use methods such as auto-complete or templates for commands to mean you do not have to remember every command and parameter.
Oddly many interfaces are getting worse in this regard as they require you to discover and remember complex touch or mouse gestures.