Copyright 1999 all rights reserved Select the Proper Kinds of Windows
Copyright 1999 all rights reserved Human Task Switching n Types of Task Switching –Interruption –Need to find missing process or information –Human initiated rest n Effect of Task Switching –Cognitive attention lost –Cognitive load increases
Copyright 1999 all rights reserved Task Switching - Interruptions n For today’s Information Worker –interruptions are part of individual’s day many people are interrupted 10 times in each short task many people are interrupted 10 times in each short task –interruptions require the individual to: either search for their location in the task they are doing either search for their location in the task they are doing or mentally record where they are in the task or mentally record where they are in the task
Copyright 1999 all rights reserved Task Switching - Self initiated n People also interrupt their own task –many tasks are complex enough that humans lose track of where they are and restart them –many tasks are cognitively demanding and require mental rests humans switch to reading their or more routine tasks for this rest humans switch to reading their or more routine tasks for this rest
Copyright 1999 all rights reserved Task Switching--Incomplete Preparation n People do not organize and plan their work for the week, day, hour except in a very general way n People carry out the next detailed part of their task based on the visual and auditory cues that are currently present in their task
Copyright 1999 all rights reserved Knowledge - Norman n In the head...and in the world n We behave precisely without precise knowledge –Information is in the world –Natural constraints are present –Cultural constraints are present –Precise memory is not required
Copyright 1999 all rights reserved Knowledge in the Head vs. in the World
Copyright 1999 all rights reserved Incomplete Preparation n Example –Cooking potatoes: after the potatoes have been washed, we use the visual cue of the washed potatoes with skins on to tell us we have to peel them –Similarly, when they are peeled, we know the next step is to cook them
Copyright 1999 all rights reserved Incomplete Preparation n Use of external cues to tell us where we are in the task is known as Situated Action n Reliance on situated action means that we often remember we need a crucial piece of information only in the middle of the task
Copyright 1999 all rights reserved Incomplete Preparation n For example, in cooking the potatoes, we may suddenly realize we need salt and have to run to the store to get salt n In short, we are not really forgetful; it is cognitively easier for us to do the task via situated action then to plan ahead n This leads to lots of task switching
Copyright 1999 all rights reserved Effect of Task Switching n Loss of task attention –Tasks require place-keepers for people to return to them at the point where they switched away –If the place-keepers are not available visually, they have to be maintained mentally –Even with visual place-keepers, there is some mental overhead in task switching
Copyright 1999 all rights reserved Task Switching Management n Because task switching is inherent in the social and psychological makeup of human work, humans have developed strategies for handling it –they lay out their work on a surface to be able to move from task to task –they create patterns in their layout to help them find and return to a particular task
Copyright 1999 all rights reserved How People Manage their Desktops n People have done studies of how people manage their desk in hopes of providing computer tools to support the task n People are either orderly or very messy, but the real issue here is that people have a visual sense of the layout of papers n They use this visual picture to help them find things
Copyright 1999 all rights reserved How People Manage their Desktops n People lay out items on their desk as reminders n People lay out items on their desk so they can do task switching n People lay out items on their desk so they can see the relationships among the items
Copyright 1999 all rights reserved Windows: Support for Task Switching n In the beginning, people had one application running on their computer at a time n Because we are constantly switching tasks, this became intolerable – exit program 1 – enter program 2 – exit program 2 – enter program 1 n Windows solve this problem
Copyright 1999 all rights reserved Windows: Our Virtual Messy Desk! n People use windows exactly like they use stacks of papers on their desks n But: task switching with windows is often like searching a very messy desk – built by programmers for programmers – windows appear in strange places and inconvenient sizes – like the QWERTY keyboard, we now must live with them
Copyright 1999 all rights reserved Windows n Overview n Components n Presentation styles n Types n Organization n Operations Chart-o-maticX
Copyright 1999 all rights reserved Some Uses of Windows n Support for human user – Provide knowledge in the world – Reflect the way people work n Presentation of information – Different levels, kinds, and sequences – Different sources n Performing more than one task n Reminding n Monitoring
Copyright 1999 all rights reserved Windows Components
Copyright 1999 all rights reserved Window Components--Win 98
Copyright 1999 all rights reserved Window Presentation Styles n Tiled – Single task activities – Tasks with little window manipulation – Novice or inexperienced users n Overlapping and cascading – Switching between tasks – Window manipulation needed – Expert or experienced users Disadvantages of each type ?
Copyright 1999 all rights reserved Disadvantages of Presentation Styles n Tiled –Limited screen size –Open windows change size & position –Windows get tiny –Look crowded –Less user control n Overlapping –More complex, possibly distracting –Information gets hidden or lost –Users don’t always recognize 3-D model
Copyright 1999 all rights reserved Types of Windows n Primary or Application n Secondary, Document, or Supplemental – Property Windows – Dialog Boxes Modal or Modeless Modal or Modeless – Message Boxes – Palette Windows – Pop-Up Windows (e.g., paper clip guy)
Copyright 1999 all rights reserved Property Windows n Displays accessible properties of object n Information is grouped using tabbed pages
Copyright 1999 all rights reserved Dialog Boxes n Get additional information from user n Common dialogs –Open –Save –Print
Copyright 1999 all rights reserved Message Boxes n Provides information to the user n Standard types –Information –Warning –Critical error
Copyright 1999 all rights reserved Palette Windows n Presents a collection of controls-- graphical or pictorial n Mutually exclusive choices--like radio buttons –Palettes –Toolbars
Copyright 1999 all rights reserved Pop-Up Windows n Displays additional information n Most standard secondary window components omitted n Example: tooltips
Copyright 1999 all rights reserved Types of Windows n Single Document Interface (SDI) n Multiple Document Interface (MDI) n Workspaces n Workbooks n Projects
Copyright 1999 all rights reserved MDI Windows
Copyright 1999 all rights reserved Organizing Windows n Organize windows to support user tasks –Rather than organizing by features, functions, or ease of implementation n Minimize the number of windows needed to perform a task –Focus on common tasks
Copyright 1999 all rights reserved Sizing Windows n Large enough to – Contain expected information – Avoid hiding important information – Avoid crowding n Otherwise, as small as possible! – Text - about 12 lines – Alphanumeric - about 7 lines
Copyright 1999 all rights reserved Window Operations n General Guidelines – Focus on ease of use and learning – Less is more – Give users control / ability to tailor Especially for overlapping windows ! Especially for overlapping windows ! n Keyboard Control/Mouseless Operation Opening…Placement…Separation…Moving… Resizing…Shuffling…Closing
Copyright 1999 all rights reserved Limitations of Windows n Little research on window design/use n Hardware limitations n Human limitations