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2.3 Conceptual models 49

fied of dragging the icon of their floppy disk to the trash can icon on the desktop to
eject it from the computer for fear of deleting it in the same way files are when
placed in the trash can. The conceptual confusion arises because the designers
opted to use the same action (dropping) on the same object (trash can) for two
completely different operations, deleting and ejecting. Another problem is that not
all tasks can be described by objects and not all actions can be done directly. Some
tasks are better achieved through issuing instructions and having textual descrip-
tions rather than iconic representations. Imagine if email messages were repre-
sented as small icons in your mailbox with abbreviations of who they were from
and when they were sent. Moreover, you could only move them around by drag-
ging them with a mouse. Very quickly they would take up your desk space and you
would find it impossible to keep track of them all.

4. Exploring and browsing
This conceptual model is based on the idea of allowing people to explore and
browse information, exploiting their knowledge of how they do this with existing
media (e.g., books, magazines, TV, radio, libraries, pamphlets, brochures). When
people go to a tourist office, a bookstore, or a dentist's surgery, often they scan and
flick through parts of the information displayed, hoping to find something interest-
ing to read. CD-ROMs, web pages, portals and e-commerce sites are applications
based on this kind of conceptual model. Much thought needs to go into structuring
the information in ways that will support effective navigation, allowing people to
search, browse, and find different kinds of information.

What conceptual models are the following applications based on?

(a) a 3D video game, say a car-racing game with a steering wheel and tactile, audio, and
visual feedback
(b) the Windows environment
(c) a web browser

Commenf (a) A 3D video game is based on a direct manipulation/virtual environment conceptual
model.
(b) The Windows environment is based on a hybrid form of conceptual model. It com-
bines a manipulating mode of interaction where users interact with menus, scrollbars,
documents, and icons, an instructing mode of interaction where users can issue com-
mands through selecting menu options and combining various function keys, and a
conversational model of interaction where agents (e.g. Clippy) are used to guide
users in their actions.
(c) A web browser is also based on a hybrid form of conceptual model, allowing users to
explore and browse information via hyperlinks and also to instruct the network what
to search for and what results to present and save.