236: II'nMI

A CogPsych Teaser +

The Big Six Normanisms

Would you notice?

Would you notice?

It depends.• Conspicuity: sensory contrast and/or cognitive relevance

• Mental workload + task interference

• Expectation (may miss unusual events)

Would you notice?

“A good conceptual model of events allows us to classify them into those relevant and those not relevant, dramatically simplifying life: we attend to the relevant and only monitor the irrelevant [subconsciously].”“Precision, accuracy, and completeness of knowledge are seldom required.”

-Donald Norman

Which direction is

Abraham Lincoln

facing on a penny:

left or right?

Would you notice?WHY would you need to notice, anyway?

“A good conceptual model of events allows us to classify them into those relevant and those not relevant, dramatically simplifying life: we attend to the relevant and only monitor the irrelevant [subconsciously].“Precision, accuracy, and completeness of knowledge are seldom required.”

-Donald Norman

Would you notice?100 billion nerve cells (1bps each) with about 10,000 connections to

other nerve cells - a million billion links

Nerve cells respond to changes in the environment. If there is no change, the sense receptors soon adapt

Our unconscious sculpts down this flood of simple details and makes complex meaning

Consciously, we think about only the most important stuff,the rest remains fuzzy ...

Attention & Automaticity

Incongruence (e.g. different keyboard)?Competing automatic routine? Danger, novelty, temptation, etc?

Needs no attention resourcesDoesn’t interfere with other activitiesNo conscious awareness - the response is activated automatically.

AutomaticWell-known information, over-learned skill, etc.

AutomaticWell-known information, over-learned skill, etc.

NOT automatic; conscious attention & effort

time

Would you notice?… the rest remains fuzzy.

This applies to memory, skill, and communication, too. We tend to operate at the big-picture level, or better - automatically.Once the unconscious has processed the detailed data (of learning to drive, of currency, of reading, of this classroom …) and integrated it with what we know/expect

we purge the low-level data.

Sensory homunculus: If each body part grew in proportion to the area of the cortex of the brain

concerned with its sensory perception.

So how do we communicate with these weird little homo sapien dudes?

Motor homunculus: If each body part grewin proportion to the area of the cortex of the brain

concerned with its movement.

Steroid homunculus: If each body part grewin proportion to the area of the cortex of the brain

flooded with testosterone.

Signals things can send…

Pull me sideways!

Pull me up!

Turn me!

A card could slide in here ...

You should walk here, not there.

The Big Six Normanisms• Affordances

• Constraints

• Visibility

• Mapping

• Feedback

• Conceptual model

The Big Six Normanisms

Know them.Use them.Love them.

They will serve you well,both in this class ... and beyond!

AffordancesAffordance: a property of a device that enables it to be used.

• The grip of a pistol affords holding.

• The barrel sight affords aiming.

• The trigger affords pulling (and shooting).

Subjective/objective affordances• Subjective (perceived) affordances of a pistol include: holding, aiming, and shooting .

• Objective affordances: hammer a nail into wood, use as a paperweight, hang by a wire from the ceiling as a mobile.

ConstraintsConstraint: a property of a device that limits its usage.

• The trigger guard of a pistol constrains the number of fingers that can be used to pull the trigger to one (or perhaps two).

• The physical relationship between the grip and the trigger constrains which finger(s) can be used to pull the trigger (e.g., not the thumb).

• The engineering of the trigger constrains the direction it can be moved (backward).

Misperception: Constraint = bad = missing functionality• On the contrary, intelligent use of constraints can greatly increase and simplify an object’s

usability.

VisibilityVisibility: the degree to which a device's intended use is visible (apparent) to the user.

• The shape of a pistol (grip, barrel, trigger) makes the way it is intended to be held quite visible.

• The location and movement of the trigger guard and trigger make the act of pulling the trigger reasonably visible.

• The long straight barrel with a hole in one end makes the act of shooting the pistol somewhat, though by no means clearly, visible.

What is the intended use of this object (next page) ... ?

What do I do?

Mapping

Mapping: the relationship between the controls of a device (knobs, switches, levers, buttons, pedals, keys, etc.) and what these controls can be used for.

• Consider the mappings of a pistol:– The grip maps to holding the pistol.

– The barrel sight maps to aiming.

– The trigger maps to shooting.

Oy!

MappingNatural mapping: a mapping that uses physical analogies and cultural standards to make it easy to understand.

• The shape of a pistol and everyday laws of physics make it clear that the barrel of a pistol should be pointed at the intended target.

• The engineering of the trigger guard (lots of space in front of the trigger, very little behind) make it clear that the trigger should be pulled backwards to shoot.

• The safety switch, on the other hand, is not naturally mapped, and for this reason users must work at learning how to use it properly.

Natural design: design that makes use of natural mappings.

FeedbackFeedback: information a device communicates back to users about actions they have taken.

• Feedback shows users the effects of their actions.

• Setting a pistol safety switch to its on or off position might produce an audible feedback click or a palpable drop into a slot.

• Loading a bullet properly in the breach might produce an audible and palpable snap.

• Shooting produces an audible report and palpable recoil.

Without clear and timely feedback, users can feel lost, clueless, annoyed, unsure how to proceed.

Conceptual ModelsConceptual model: a mental image of how a device works.

• There are two types of conceptual models:– Design model

• the designer's mental image, emerges from designing the device

– User model

• the user's mental image, emerges from interacting with device

• In general, the closer the user model is to the design model for a device, the more understandable the device is for the user.

• The design and user models for a pistol are very similar: a pistol is a device that shoots bullets at targets.

• The models diverge to some extent when it comes to details: how to load the bullets, how to use the safety, how to minimize recoil, etc.

Assignment: Big Bad Design Scavenger Hunt

Let's have a look: • BBDSH