Untangling search task complexity and difficulty in the context of interactive information retrieval studies

Abstract

Purpose – One core element of interactive information retrieval (IIR) experiments is the assignment of search tasks. The purpose of this paper is to provide an analytical review of current practice in developing those search tasks to test, observe or control task complexity and difficulty. Design/methodology/approach – Over 100 prior studies of IIR were examined in terms of how each defined task complexity and/or difficulty (or related concepts) and subsequently interpreted those concepts in the development of the assigned search tasks. Findings – Search task complexity is found to include three dimensions: multiplicity of subtasks or steps, multiplicity of facets, and indeterminability. Search task difficulty is based on an interaction between the search task and the attributes of the searcher or the attributes of the search situation. The paper highlights the anomalies in our use of these two concepts, concluding with suggestions for future methodological research related to search task complexity and difficulty. Originality/value – By analyzing and synthesizing current practices, this paper provides guidance for future experiments in IIR that involve these two constructs.

How fast is too fast? evaluating fast forward surrogates for digital video

“…The design was intended to isolate the effects of surrogate speed, and so could not take into account the effects of potential interactions with other surrogate features if implemented in context. For example, no audio was provided with the fast forward surrogates investigated here; yet, it is likely that a fullyfunctioning digital library interface would incorporate audio (such as the audio keywords investigated in a previous study [25]). Similarly, these surrogates were viewed in isolation; in a fully-functioning interface, it is likely that users would have viewed additional metadata (e.g., video title or poster frame) before accessing the fast forward surrogates.…”

“…In a previous study [25], participants raised the notion that an important component of video materials is the motion perceived in viewing them. Thus, surrogates that simulate this motion (even in high speed) can help people comprehend the video's gist more completely.…”

“…Other possibilities identified as relevant video characteristics in our research framework (see Figure 1) include the rate of scene change, homogeneity of content [25] or other topical or stylistic features. These video characteristics should be investigated through additional analyses of data from the current study, as well as through additional studies.…”

“…Visual gist comprehension: Select objects that "belong" in the video represented by the surrogate, from a set of still images. These tasks were selected for development because they closely relate to the tasks in which users engage when interacting with a library of digital videos [25]. The object recognition tasks are most closely related to the user goal of selecting particular frames from a video, just as the action recognition task is most closely related to the user goal of selecting a particular clip.…”

“…This type of fast forward surrogate 1 is created by sampling from the video frames (rather than speeding up the display of the frames), but the result for the person viewing the surrogate is the ability to speed through the video much faster while still being able to perceive the images. In pilot studies and in a previous study that compared slide show, storyboard, and fast forward surrogates [25], fast forwards constructed in this Nth frame fashion were judged to be effective and realistic by users. Thus, the fast forward surrogates used in this study are an approximation of what may be both technically possible and also useful from the human perceptual system point of view.…”