Direct Manipulation and Multi-touch Interactions

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Principles of direct manipulation:

  • Principle of virtuality - user can enjoy and able to manipulate some version of reality.
  • Principle of transparency - UI disappears allows user to apply intellect to task and logical thinking.
  • Gulf of execution and gulf of evaluation - related to psychology literature on problem-solving and leaning research.

Advantages of using direct manipulation:

  • Continuous visual representation of objects and action of interest.
  • Physical action instead of syntax.
  • Rapid incremental and reversible actions whose results are visible immediately.
  • Novices learn quickly.
  • Users gain confidence and mastery.

Problems in direct manipulation:

  • Blind / vision - impaired: if we develop for a visual interface, this group might be left out.
  • Screen space- It takes up plenty, possible abuses, multiple pages can slow user down.
  • Typing commands are using shortcut keys with the keyboard can make faster.
  • The users must learn the semantics behind the graphical representation.
  • Design will force valuable information off the screen.
  • High level flowcharts and database schema can become confusing.


Hardware technologies:

  • Camera and image processing
  • When the finger is pressed on glass, camera detects the action and register as input. Then the image processing sequence is processed and it will adjust the image back ground from current camera image.

  • Touch-sensitive capacitance sensors
  • The touch screen consists of insulator such as glass, coated with a transparent conductor. The human body is also a conductor, so while touching the screen results in a distortion of body's electrostatic field. The location is then passed to software application running in computer.

Advantages of multi-touch interaction:

  • It replaces the input devices such as keyboard, mouse and even stylus with an invisible interface
  • It enables user to manipulate new functions like optical clarity, durability and cost- effective implementation of multi touch features.
  • It allows multiple users interaction with software.
  • It lets to do without requiring any intermediate device.
  • This interface has potential to alter the way we work with data and applications, resulting in more dynamic interactions around content.
  • It enables the user to interact which is directly displayed on screen.

Problems in multi-touch interaction:

  • Some users may feel uncomfortable to adopt an entirely new method of using computers.
  • It may present a barrier to users with visual impairments or disabilities that would limit physical dexterity.
  • These systems are relatively expensive.
  • Few applications developed for Microsoft surface have been piloted in small number of AT&T stores.
  • Selecting detailed object with fingers is difficult.
  • It is not suitable for inputting large amount of data.


When multi- touch interaction method is approached direct manipulation is simultaneously added to it. The support of direct manipulation with multi- touch interface starts from the experience it offers. When the users slides their fingers along a touch surface, the object act by translating, rotating and scaling themselves so that the point of the finger remains same. Without the need for any ambiguous gesture processing, direct manipulation intrinsically provides controllable and an innate mapping between points in screen space and in local space.

An example for this is iPhone. The iPhone is not a ordinary phone rather it is a multi- purpose portable touch screen computer. The iPhone users surveying report gives very high level of satisfaction with this product. The most important effect of the iPhone is fundamental challenge to mobile phone industry. It is "candy bar" style device. The front screen is dominated by touch- sensitive 320x480 and doesn't have keypad. It weighs 135gms- heavy compared to simple phone. It includes a quad- band GSM/edge cellular radio (without 3G), WiFi (802.11 b and g), Bluetooth 2.0 and a two megapixel camera.


  • This device has no stylus and designed for finger-driven.
  • It enables user to manipulate the interface via gestures.
  • Apple is one of the first companies to implement in a commercial product.
  • It includes some features which are uncommon in other products. One is proximity sensor turns off the touch screen when the device is close to user's face. Another is position sensors to rotate screen image appropriately, when the device is turned sideways.
  • The interface is really elegant and intuitive. The icons are big and bold so want to make "fat finger" errors.
  • There is variety and number of application in App store is almost staggering.
  • The web browser is real.
  • The speed is very good.


  • A physical QWERTY keyboard as in palm Treo and RIM blackberry devices is missing.
  • Unable to install third party applications.
  • Unable to read and edit Microsoft office documents.
  • No user-replaceable battery.


2 megapixel camera - even Nokia N95 have 5 megapixel, apple failed to update the dated pixel to the camera.

  • Battery life - durability of 5 hours talk time is very low compared to other mobiles like Motrola Q.
  • No expansion slot - memory of 32 GB is high but sometimes cant accommodate new movies
  • No 3G.
  • Non removable battery.


  • Contacts - as in phone, exporting contacts from phone to sim is not available.
  • Can't use as external storage device, even though it has 32GB storage capacity.
  • Bluetooth - unable to share mp3, images and video via Bluetooth.

Alternative design

No need of alternative design it's already a good design.