Multi-Sensory Feedback (7) - By Yasmin Aftab

Ernst, Banksô and BÏlthoff in their publication: “Haptic feedback affects visual perception of surfaces.” (http://www.kyb.tuebingen.mpg.de/publication.html?publ=228, present effects of the introducing, Haptic feedback and it is influence on visual perception of surfaces. Their work shows that all designers which try to merge more than one feedback in one solution should remember about the influence of every feedback on each other. Introducing new feedback changes the weights of the rest of elements in the final output presented to the user. In the research mentioned above, this situation occurred during implementing Haptic feedback to existing visual output.

We conclude that giving Haptic feedback consistent with one cue causes its weight to increase in a purely visual task”.

Therefore, new feedbacks affect the perception of the whole product what should be taken into account during the design process. There are also other problems which designers meet during creating multi feedback interfaces. Those additional feedbacks affect the whole product, can in certain situations make it more difficult to use and discourage users from new technologies when, in fact, they should always improve products’ usability. Some difficulties come from the fact that humans perceive things differently while receiving different types of signals or multiple feedbacks instead of a single one, by introducing additional feedback we can loose some information being passed to the user.

It can happen because not every feedback transmits the information with the same accuracy and when several feedbacks are implemented, the user concentrates on ‘the easier to perceive’ feedback – not necessarily the most accurate one. As an example we can state here two feedbacks: visual and auditory. The user generally will not concentrate on the content of the screen as it is easier for him to hear the results instead of to analyse the screen and additionally he does not have to stay in front of the computer all the time.

The imperfection of digitally created speech as a feedback has been observed by Nicole Yankelovich, Gina-Anne Levow and Matt Marx during the preparation of an experimental conversational speech system and described in the document: “Designing SpeechActs Issues in Speech User Interfaces

http://people.cs.uchicago.edu/~levow/papers/CHI_95/chi95.pdf). In the summary of the document they state that finally we have strong evidence to suggest that translating a graphical interface into speech is not likely to produce an effective interface. This conclusion was made by analysing the accuracy of this feedback and dealing with problems like, the difficulty users have in interpreting silence, lack of “immediate and informative feedback” and much more.

Therefore, implementing new feedback does not necessarily improve product’s usability as this ‘new way’ of communication can be less accurate and more error prone. It is a serious problem especially, when the accuracy and correctness of the data obtained from the product have a critical value for the success of the whole process.