The secrets of perfect user interfaces

What is common between an artist in the state of inspiration and a user visiting a web site? Why some interfaces are user-friendly and others make us look away?

Interface flow

Mihály Csíkszentmihályi in 1990 described the state of flow that people get in when they are fully immerced in an exciting activity and enjoy what they are doing. This state emerges on the border between “too simple” and “too difficult”.

This state is familiar to athletes, artists, musicians and business people. Anyone can experience it given the right conditions.

Information search, playing a game, reading, buying at online store can also be accompanied by the state of flow. It allows to not only solve one’s problems more efficiently, but also to evaluate one’s user experience in a more positive light:

  • Activity is seen as a reward in itself
  • One finds satisfaction in carrying out actions
  • One zones out from the external world

Factors responsible for creating the state of flow help us create perfect user interfaces.

Toxic interfaces

The external world is the first “user interface” that any person interacts with since the first birthday. The laws of such interactions are viewed as “natural”.

How would one feel when an object behaves contrary to one's expectations? It evokes the feeling of danger. It gives an idea that the object should be avoided. That is why people refuse to use imperfect, “toxic” interfaces.

In this article you'll learn how to support the state of flow with the interface's natural reactions to human actions.

Interaction time

Three flow factors correspond with interface reactions:

  • Attention focus
  • Immediate reaction
  • Sense of control

The physiology of perception dictates that each factor has its own time frame.

40 ms: subconscious phase. That's when the person decides if he or she likes an object, but cannot yet realize this decision or notice any changes in the object.

60 ms: attention phase. That's how long it takes to pay attention to the object without a conscious reaction to the stimulus.

150-200 ms:  conscious phase. The person understands what has happened and excersizes conscious control over the situation.

>250-300 ms: losing focus. It's common knowledge that even if we try to focus, eyes stop execute rapid movements for split seconds only.


Changes in the interface that are too quick can go unnoticed or cause troubles with understanding. That's why reactions should be neither fast nor slow, but scheduled in time.

The attention phase should correspond with noticeable changes in the interface, from no less than 20-30% to the total change of the object, its form, colour, and placement. The optimal time for this phase is 60 ms.

If the object has changed and returned to the previous state in less time, it will be noticed only at the unconscious level, which exceeds the limits of interface design and relates to a very different sphere of interactions with users.

Attention focus

The total time of realization takes 150-200 ms. This is the perfect time for full interface elements reactions.

Animation that is faster will be viewed as immediate and subconsciously treated as a warning sign. Quick reaction of several elements with a focus change is experienced as false activation.

Sense of control

Studies in interface operation done as far back as in 1980s showed athat 350 ms represents the longest waiting time for system reaction. The user starts to think “Well, does this thing work at all?”



Tens Sunglasses

Zero Landfill


  • Interface reactions should not be immediate lest they be lead to mistakes and negative user experiences.
  • Transitions from one interface element to another should, in ideal, take 180 ms.
  • Reaction time cannot be too long; no longer than 350 ms.

We work around the clock for amazing results for our clients. We will be happy to answer your call from 10-00 AM to 8-00 PM on weekdays.


Moscow — Russia Varshavskoe highway, 28А +7 495 646 123 9


Vilnius — Lithuania Smolensko gatvė, 10c +370 5 207 81 37