Affordances in HCI: Exploring a mediated action perspective

Transcription

1 Affordances in HCI: Exploring a mediated action perspective Victor Kaptelinin University of Bergen Oslo, Nov 22, 2012

2 Affordances in HCI A concept proposed by Gibson Introduced to HCI by Norman the perceived or actual properties of the thing, primarily those fundamental properties that determine just how the thing could possibly be used A runaway concept Some examples: Affordances of the internet for political activism Affordances as context Cultural affordances Leadership affordances

3 Main claim While the Gibsonian concept of affordances relates to interaction between animals and their environments; it is of limited relevance to HCI research. In HCI affordances need to be re-conceptualized as possibilities for human, mediated action.

4 Some considerations The general value of Gibson's fundamental insights is not questioned This analysis is specifically related to how affordances are interpreted in HCI; other areas or disciplines are not considered Post-Gibsonian developments in ecological psychology are not included in the analysis

5 Affordances according to Gibson Defined as what the environment offers the animal, what it provides or furnishes, either for good or ill. (1979) Aspects of affordances affordances are perceived directly, not through interpretation of initially meaningless raw sensory data, affordances are relational properties; they emerge in the interaction between the animal and environment, affordances are independent of the situational needs of the perceiver, natural environments and cultural environments should not be separated from one another, the theory of affordances is concerned with how affordances are perceived, not affordances per se

6 Norman s evolution 1,2, Affordances provide strong clues to the operations of things. Plates are for pushing. Knobs are for turning. Slots are for inserting things into. Balls are for throwing or bouncing. When affordances are taken advantage of, the user knows what to do just by looking: no picture, label, or instruction needed. (1988) Moreover, affordances, both real and perceived, play very different roles in physical products than they do in the world of screen-based products. In the latter case, affordances play a relatively minor role: cultural conventions are much more important. (1999)

7 Norman s evolution 3! Social signifiers replace affordances, for they are broader and richer, allowing for accidental signifiers as well as deliberate ones, and even for items that signify through their absence, as the lack of crowds on a train platform. The perceivable part of an affordance is a signifier, and if deliberately placed by a designer, it is a social signifier. Designers of the world: Forget affordances. Provide signifiers. (2008)

8 Is forgetting affordances realistic? Probably not: Signifiers do not seem to be a strong alternative The genie is out of the bottle A number of analysis of affordances, many criticize Norman for deviating from Gibson, who originated the concept of affordances.

9 Gibsonian affordances vs. Selected HCI interpretations Relational property Directly perceived Independent of actor s needs Same in natural and cultural environments Concern with perception, not affordances per se Norman (1989, 1999) /+ +/ Gaver (1991, 1992) McGrenere & Ho (2000) Baerentsen & Trettvik (2002) +

10 Dealing with conceptual inconsistency Therefore, many interpretations of affordances in HCI are not consistent with Gibson Possible strategies for dealing with the inconsistency Make sure the uses of affordances in HCI are consistent with the Gibsonian meaning Abandon the term, e.g., in favor of signifiers (Norman, 2008) A third strategy is conceptual re-grounding

11 Re-grounding the concept of affordances The popularity of affordances in HCI indicates that the basic idea does address the conceptual needs of the field At the same time the analysis of tools in the Gibsonian tradition is incomplete. Gibson s theory does not deal with the social and cultural aspects of the use and production of tools The impact of the use of tools on action capabilities of the actor is not taken into account We argue that HCI needs a re-grounding of the notion of affordances, that is, constructing the concept on a theoretical foundation, more suitable for analysis and support of human uses of technology

12 A mediated action perspective on technology affordances Understanding technology affordances as affordances of mediating artifacts Integration of two aspects of a tool ( actor-tool and tool-environment ) has not been systematically analyzed by Gibson Relevant HCI research Bødker (1989, 1991): aspects of interaction Beaudouin-Lafon (2000): instrumental interaction Bødker and Andersen (2005): complex mediation Relevant studies in ecological psychology Wagman and Carello (2003)

13 Two aspects of mediating artifacts: An example (webmail) Cancel message Cancelling this message will permanently discard its contents. Are you sure you want to do this? Cancel OK

14 Hotel room lock

15 Recycle station

16 A mediated action perspective on technology affordances The basic structure of an instrumental technology affordance as an integrated unit comprising two components: handling affordance and effecter affordance

17 A mediated action perspective on technology affordances Technologies also have auxiliary affordances because of complex webs of mediation, such as maintenance, aggregation, and learning affordances.

18 A mediated action perspective on technology affordances Auxiliary affordances of a mobile phone. A: back cover removal slot (maintenance); B: headset jack slot (aggregation). A B

19 GIBSON S THEORY vs. MEDIATED ACTION PERSPECTIVE Similarities Differences Gibson s theory Mediated action perspective General notion Affordances are understood as action possibilities offered to the actor by objects in the environment possibilities for animal actions in natural environment possibilities for human actions in cultural environments Relational property Affordances emerge in interaction between the actor and the world the animal and natural environment the person, tool(s), and cultural environment Dynamics Action capabilities of the actor are a result of the development of a coupling between actor and the environment relatively stable, formed by biological evolution, maturation, and long-term learning dynamic, can quickly change as a result of tool switching Role of perception Quick extraction of information about affordances is critically important for successful acting in the world occurs as an immediate outcome of placing a certain animal in a certain environment can be an outcome of learning Needs Affordances and actor s situational needs are independent of one another interrelated: tool affordances can be adjusted to situational needs

20 Example A Unclear mapping of handling affordances (clicking the Back, Install, and Cancel buttons) and effecter affordances (starting installation, reviewing changes, and exiting the wizard)

21 Example B Clear mapping of handling affordances (selecting radio buttons) and effecter affordances (resulting text changes)

22 Key points The Gibsonian concept of affordances relates to interaction between animals and their environments; it is of limited relevance to HCI research In HCI affordances need to be re-conceptualized as possibilities for human, mediated action. Instrumental technology affordances include handling affordances and effecter affordances, as well as auxiliary affordances Central focus of HCI research has been on handling affordances (probably, because of how the concept was introduced by Norman) Integrating various types of affordances, such as handling and effecter affordances, is a way to design more usable technologies

23 THANK YOU! Questions?