University of Malta CSA3080: Lecture 3 © Chris Staff 1 of 18 CSA3080: Adaptive Hypertext Systems I Dr. Christopher Staff Department of Computer Science & AI University of Malta Lecture 3: Problems that AHSs try to solve

University of Malta CSA3080: Lecture 3 © Chris Staff 2 of 18 Aims and Objectives To identify different problems experienced in normal hypertext/search engine use To motivate the rest of the study-unit

University of Malta CSA3080: Lecture 3 © Chris Staff 3 of 18 Tell me your problems… What difficulties do you experience when using –WWW –Search engine

University of Malta CSA3080: Lecture 3 © Chris Staff 4 of 18 Typical Problems… Lost in Hyperspace Cognitive overload Complexity of the search space Search-browsing Static hypertext structure Inability to cater for different users with different needs and requirements

University of Malta CSA3080: Lecture 3 © Chris Staff 5 of 18 Lost in Hyperspace syndrome Characteristics –User doesn't know where he/she is in relation to other (related) information in hyperspace –User doesn't know how to access previously visited node Reference –Nielsen, J., Lyngbæk, U., Two field studies of hypermedia usability, in Green, C., McAleese, R., (ed) Hypertext: Theory into Practice II, Intellect Press, 1990.

University of Malta CSA3080: Lecture 3 © Chris Staff 6 of 18 Lost in Hyperspace syndrome Causes –Bad GUI design –Poor organisation of information –No links to landmark sites –No/poor organisation of access history –User unfamiliarity with content/ organisation

University of Malta CSA3080: Lecture 3 © Chris Staff 7 of 18 Cognitive Overload Characteristics –Affects both users and authors –Follow links “just in case” –Too many links on a page to make decision –Don’t know when to abandon search References –Conklin, J. (1987). Hypertext : An Introduction and Survey. IEEE Computer, 20 (9), –Nielsen, J. (1990). Navigation through hypertext. Communications of the ACM, 22,

University of Malta CSA3080: Lecture 3 © Chris Staff 8 of 18 Cognitive Overload Causes –Massive information spaces –Authors expected to provide links to all relevant information... –... users won't have to think about the information they want to consume... –... implies that authors have to anticipate all the different ways in which their information might be relevant to different users

University of Malta CSA3080: Lecture 3 © Chris Staff 9 of 18 Cognitive Overload Causes (continued) –Authors cannot anticipate all the ways in which their information might be used –Authors cannot know all relevant information that exists/might exist in the future –Worst-case scenario: link everything to everything else but users will then face cognitive overload –Every time user accesses a node with more than one out-link, she has to decide which link to follow – Hyperspaces don't give guarantees about connectedness/ completeness

University of Malta CSA3080: Lecture 3 © Chris Staff 10 of 18 Cognitive Overload Causes (continued) –A user's interaction with an information base improves with familiarity –The more complex the organisation, the harder for the user to develop an accurate conceptual model of the site –Users also face cognitive overload in environments where the interface is inconsistent –7+/-2 rule

University of Malta CSA3080: Lecture 3 © Chris Staff 11 of 18 Complexity of the search space Characteristics –Cannot “guess” how document might be described –Cannot “guess” where a document might be located –Related to Cognitive Overload References –Staff, C. (2001). HyperContext: A Framework for Adaptive and Adaptable Hypertext. PhD thesis, University of Sussex. Chapters 2 and 3 ( –Van Dyke Parunak, H. (1989). Hypermedia topologies and user navigation, in Proceedings of the second annual ACM conference on Hypertext. November 1989.

University of Malta CSA3080: Lecture 3 © Chris Staff 12 of 18 Complexity of the search space Causes –Browsing is a form of search –"I'll know I've found what I want when I see it" –Advantage and disadvantage of hierarchical 'classification' systems (e.g., User has to know where to find what she wants Document must be classified correctly

University of Malta CSA3080: Lecture 3 © Chris Staff 13 of 18 Complexity of the search space Causes –Lack of link semantics - no guarantee that in general hyperspaces a link is going to lead to greater detail –The more complex the search space, the harder for the user to construct an accurate conceptual model –… and the greater the likelihood of the user getting disoriented –If the hyperspace is too simple, it probably won't cater for the needs of all possible users –If hyperspace is too small, we can 'remember' where everything is

University of Malta CSA3080: Lecture 3 © Chris Staff 14 of 18 Search-browsing I Searching and browsing are complementary tools for navigating through a hyperspace which does not provide a semantic representation of its contents Normally, search is used to identify a node that is "close" to the required node, if not the required node itself Browsing takes place so the user can understand the information content and make informed decisions about which link to follow (or to describe an information need) Sometimes also necessary, because user is unfamiliar with terminology, so needs to locate nodes which will enable user to specify more accurate query

University of Malta CSA3080: Lecture 3 © Chris Staff 15 of 18 Search-browsing II If user knows where information is, or if user knows how to get to information (from some known landmark), then search not needed If user knows what is wanted, but doesn't know location of document, then search is required Usually, search is performed at a different location from which user is browsing Search-browsing would allow user to search while browsing, and the system may enable the user to follow a recommended path to the relevant node

University of Malta CSA3080: Lecture 3 © Chris Staff 16 of 18 Static Hypertext Structure (WWW) Hypertexts are usually static Authors create hyperspace, which users traverse Hypertext generally cannot re-organise itself by learning from users Users who want to create a more easily navigable hyperspace need to create it, possibly by replicating existing resources Links cannot be modified to lead to more useful information, unless the user is the owner of the node (but see XPointer, XLink W3C standards)

University of Malta CSA3080: Lecture 3 © Chris Staff 17 of 18 Conclusion The problems described above lead to the inability to cater for users with different needs and requirements This study-unit and CSA4080 look at how these problems are being tackled using Adaptive Hypertext Systems

University of Malta CSA3080: Lecture 3 © Chris Staff 18 of 18 Definition of Adaptive Hypertext “[B]y adaptive hypermedia we mean all hypertext and hypermedia systems which reflect some features of the user in the user model and apply this model to adapt various visible aspects of the system to the user” Brusilovsky, P. (1996). Methods and techniques of adaptive hypermedia, in User Modeling and User-Adapted Interaction 6 (2-3), pp Available on-line at: