Dr Timothy Cribbin

1991-1994 BSc (Hons) Psychology (Portsmouth)
1995-1996 MSc Industrial Psychology (Hull), awarded Tom Hoyes memorial prize for dissertation (see)
1998-2000 EPSRC funded research assistant at Psychology Institute, Aston University (PI: Dr Steve Westerman)
2000-2001 LIC funded research assistant at DISC, Brunel University (PI: Dr Chaomei Chen)
2000-2005 PhD (Brunel)
2001-present Lecturer, DISC, Brunel University

Research Interests

Information visualisation, document similarity analysis, interactive information retrieval, human-computer interaction

In recent years, following early work that examined depth perception in desktop VR (Westerman and Cribbin, 1998), my main interest has been in the development and evaluation of methods for visualizing document corpora, with a specific focus on the document spatialization approach. Spatialization employs the distance-similarity metaphor to create point, network or tree maps that summarise the semantic relationships between documents in a corpus. If designed and implemented correctly such maps can provide both a thematic overview and a context within which to browse and explore. Key publications have investigated the usability of spatializations, considering the effects of individual differences, for a variety of information seeking tasks (Westerman and Cribbin, 2000; Cribbin and Chen, 2001; Chen et al., 2002 ).

Although supervised methods (classification) can be used, I am most interested in how to generate useful spatializations, quickly, from unstructured and/or noisy text, using unsupervised feature modelling (text analysis) and dimension reduction techniques. Given that term-document feature spaces tend to be sparse and non-linear in structure, my recent focus has been on graph-theoretic approaches to modelling and visualizing document proximity. My PhD (Cribbin, 2006) demonstrated how spatializations generated from minimum-spanning tree (MST) graphs of document dissimilarity, provide a superior alternative to conventional multidimensional scaling (MDS) for visualizing the structure of complex (multi-aspect) topics. I also proposed two novel interactive interactive techniques (see image) to support visual navigation and exploration. Concept signposts are contextually relevant key words that are used to dynamically label neighbours of a selected document. The idea is that while the spatial-semantic structure tells the user which documents are neighbours, signposts explain why they are related. Concept pulses, on the other hand, allow the user to see quickly how locally salient words and phrases are distributed more globally across the document map by dynamically inflating then deflating document nodes according to their degree of match.

More recently, I have extended my PhD work by looking at more datasets and testing other graph pruning methods, including KNN and Pathfinder Associative Networks (PFNET), as a basis for computing geodesic distances within the Isomap method. I show in Cribbin (2009) how Isomap better preserves the aspectual structure of a set of news search results compared to non-metric MDS. Also, whilst Isomap applications usually estimate geodesic distances from a KNN graph, I show that MSTs are just as effective and eliminate the problems of short-circuits and disconnectedness that normally require manual fine-tuning of the K parameter.

Realising the potential of Isomap (and other non-linear, proximity based dimension reduction methods), my latest work has been to develop a more efficient and scaleable way of computing the weighted NN graph of inter-document dissimilarities. Normally it is necessary to use a brute-force approach to determine the exact nearest neighbours graph, MST or PFNET, which has a complexity equal to the dimensionality, M, times the number of document pairs i.e. O(MN^2). Neighbour Estimation by Lexical Signatures (NELS) avoids the need to compute the complete matrix of full-vector inter-document dissimilarities by estimating the likely neighbours of each document according to their similarity to its lexical signature (Phelps and Wilensky, 2000). The number of expensive, full vector dissimilarity computations is reduced from N^2 to FKN, where K is the neighbourhood size and F is some small constant (F=2 produces good results) Early trials with NELS show run-time savings increasing linearly with set size, to a factor of 8 for a set of 500 documents (Cribbin, submitted) and in the order of 25 times for a set of 2200 documents, with little or no loss of spatial-semantic fidelity in the final Isomap solutions. Further refinements are being tested to improve the efficiency of the NELS approach. For instance, pruning the vocabulary prior to the final edge weighting step can improve speed further by a factor of 2 or more, whilst better signature term selection criteria can even improve the validity of nearest neighbour edge selections over the exact method, without harming efficiency.

Emerging interests include how cognitive theory and related methodologies can inform the development of more valid and contextually sensitive algorithms for computing document-similarity and how social navigation and document usage data can be directly and indirectly exploited to enrich and facilitate the information seeking experience.

I am currently a member of People and Interactivity Research Centre (PIRC) within the Department of Information Systems and Computing.

de Folter, J. and Cribbin, T (under review) Stimulating insight of a counter-current chromatography model using visualisation and dynamic querying.

Cribbin, T (under review) Discovering latent topical structure by second-order similarity analysis.

Cribbin, T. (under review) Fast document neighbour graph estimation using lexical signatures.

Cribbin, T. (accepted, Jan 2009). Visualising the structure of document search results: a comparison of graph theoretic approaches. Information Visualization. DOI

_{Cribbin, T. (2006).
Classifying complex topics using spatial-semantic document
visualization: an evaluation of an interaction model to support
open-ended search tasks. Unpublished PhD, Brunel University,
Uxbridge, UK. BURA}

_{Westerman, S. J.,
Collins, J., & Cribbin, T. (2005). Browsing a document
collection represented in two- and three-dimensional virtual
information spaces. International Journal of Human-Computer
Studies, 62(6), 713-736. DOI}

_{Morar, S. S., Macredie, R., &
Cribbin, T. (2002). An investigation of visual cues used to create
and support frames of reference and visual search tasks in desktop
virtual environments. Virtual Reality, 6(3), 140-150. BURA DOI}

_{Chen, C., Cribbin, T., Kuljis, J.,
& Macredie, R. (2002). Footprints of Information Foragers:
Behaviour Semantics of Visual Exploration. International Journal
of Human-Computer Studies, 57(2), 139-163. DOI BURA
(post-print)}

_{Chen, C., Cribbin, T., Morar, S.
S., & Macredie, R. (2002). Visualizing and Tracking the Growth
of Competing Paradigms: Two Case Studies. Journal of the American
Society for Information Science and Technology, 53(8),
678-689. DOI}

_{Westerman, S. J., Cribbin, T.,
& Wilson, R. (2001). Virtual information space navigation:
Evaluating the use of head tracking. Behaviour and Information
Technology, 20(6), 419-426. DOI}

_{Morar, S. S., Macredie, R., &
Cribbin, T. (2001). Perceiving depth in desktop virtual
environments: Effects of motion parallax and object placement.
Paper presented at INTERACT 2001, Tokyo,
Japan.}

_{Morar, S. S., Macredie, R. D.,
& Cribbin, T. (2001). A Study of the Relative Importance of
Visual Cues in Desktop Virtual Environments. Paper presented at
HCI International 2001, New Orleans, USA.}

_{Cribbin, T., & Chen, C. (2001,
5-10 August). A study of navigation strategies in
spatial-semantic visualisations. Paper presented at the HCI
International 2001, New Orleans, USA. BURA
(post-print)}

_{Cribbin, T., & Chen, C. (2001,
9-13 July). Exploring Cognitive Issues in Visual Information
Retrieval. Paper presented at the Eighth IFIP TC.13 Conference
on Human-Computer Interaction, INTERACT 2001, Tokyo, Japan.
BURA
(pre-print)}

_{Cribbin, T., & Chen, C. (2001,
January 21-26). Visual-Spatial Exploration of Thematic Spaces: A
Comparative Study of Three Visualisation Models. Paper presented
at Electronic Imaging 2001: Visual Data Exploration and Analysis
VIII, San Jose, CA. PDF
(post-print)}

_{Chen, C., & Cribbin, T.
(2001). Visualising and animating visual information foraging in
context. Paper presented at HCI International 2001, New Orleans.
BURA
(post-print)}

_{Westerman, S. J., & Cribbin,
T. (2000). Cognitive ability and information retrieval: When less is
more. Virtual Reality, 5(1), 1-7. DOI}

_{Westerman, S. J., & Cribbin,
T. (2000). Mapping semantic information in virtual space:
Dimensions, variance, and individual differences. International
Journal of Human-Computer Studies, 53(5), 765-788. DOI}

_{Westerman, S. J., & Cribbin,
T. (1999). Navigating Virtual Information Spaces: Individual
Differences in Cognitive Maps. Paper presented at UK Virtual
Reality Special Interest Group Conference, Salford,
England.}

_{Cribbin, T., & Westerman, S.
J. (1999, August 30-September 3). Spatial Data Management
Systems: Mapping Semantic Distance. Paper presented at INTERACT
99, IFIP TC.13 International Conference on Human-Computer
Interaction, Edinburgh, Scotland.}

_{Cribbin, T. (1999, August
30-September 3). Spatial Data Management Systems: Human Factors
Perspectives. Paper presented at INTERACT 99, IFIP TC.13
International Conference on Human-Computer Interaction, Edinburgh,
Scotland.}

_{Westerman, S. J., & Cribbin,
T. (1998). Individual differences in the use of depth cues:
Implications for computer- and video-based tasks. Acta
Psychologica, 99(3), 293-310. DOI}