Gerhard Strube

Web search behavior of Internet experts and newbies

Abstract Searching for relevant information on the World Wide Web is often a laborious and frustrating task for casual and experienced users. To help improve searching on the Web based on a better understanding of user characteristics, we investigate what types of knowledge are relevant for Web-based information seeking, and which knowledge structures and strategies are involved. Two experimental studies are presented, which address these questions from different angles and with different methodologies. In the first experiment, 12 established Internet experts are first interviewed about search strategies and then perform a series of realistic search tasks on the World Wide Web. From this study a model of information seeking on the World Wide Web is derived and then tested in a second study. In the second experiment two types of potentially relevant types of knowledge are compared directly. Effects of Web experience and domain-specific background knowledge are investigated with a series of search tasks in an economics-related domain (introduction of the Euro currency). We find differential and combined effects of both Web experience and domain knowledge: while successful search performance requires the combination of the two types of expertise, specific strategies directly related to Web experience or domain knowledge can be identified.

Preferred and Alternative Mental Models in Spatial Reasoning

The mental model theory postulates that spatial reasoning relies on the construction, inspection, and the variation of mental models. Experiment 1 shows that in reasoning problems with multiple solutions, reasoners construct only a single model that is preferred over others. Experiment 2 shows that inferences conforming to these preferred mental models (PMM) are easier than inferences that are valid for alternatives. Experiments 3 and 4 support the idea that model variation consists of a model revision process. The process usually starts with the PMM and then constructs alternative models by local transformations. Models which are difficult to reach are more likely to be neglected than models which are only minor revisions of the PMM.

Answering survey questions: The role of memory

Many survey questions make more than neglegible demands on the respondent’s memory. Not only do they tap semantic knowledge (required to understand what the interviewer is saying), or ”world knowledge” (e.g., who is President), but they draw on episodic or biographical memory as well. ”When did you last visit a medical doctor?” asks for a date, which usually has to be supplied from memory - not from a notebook where most people write dates down so that they do not have to bother their memory with them. A similar question from the US National Health Interview Survey is even harder, although it only asks for an approximate answer: ”During the past 12 months, about how many times did you see or talk to a medical doctor?” Ideally, the respondent should skim through memory as though it were a calendar, picking relevant episodes, and estimating the one-year span. Obviously, real respondents just cannot do that without making errors, although they try. Most try a ”past-to-present” strategy, which seems the second best way to get accurate results (Fathi, Schooler, & Loftus, 1984).

Syntactic Ambiguity Resolution In German

This chapter discusses sentence processing research from differential perspective and from universal perspective. It argues the ways in which the peculiarities of German give the opportunity to provide a new test ground for theories of sentence processing in general. The chapter explains evidence on constructions which are highly comparable, not only in German and English, but also many other languages. It discusses constraints on models of human sentence processing in general which can be derived from experiments on German. The chapter talks about attachment preferences and the principle of parameterized head attachment based on experiments on PP- and NP attachment as well as extensions of the models which have proven to be necessary to explain relative clause attachment preferences. Keywords: clause attachment preferences; English; German; parameterized head attachment; sentence processing research

Are There Limits to Binaural Additivity of Loudness

In recent years there has been notable interest in additive models of sensory integration. Binaural additivity has emerged as a main hypothesis in the loudness-scaling literature and has recently been asserted by authors using an axiomatic approach to psychophysics. Restrictions of the range of stimuli used in the majority of former experiments, and inherent weaknesses of the axiomatic study by Levelt, Riemersma, and Bunt (1972) are discussed as providing reasons for the present investigation. A limited binaural additivity (LBA) model is proposed that assumes contralateral binaural inhibition for interaural intensity differences that exceed a critical level. Experimental data are reported for 12 subjects in a loudness-matching task designed to test the axioms of cancellation and of commutativity, both necessary to the existence of strict binaural additivity. In a 2 X 2 design, frequencies of 200 Hz and 2 kHz were used, and mean intensity levels were 20 dB apart. Additivity was found violated in 33 out of 48 possible tests. The LBA model is shown to predict the systematic nonadditivity in the loudness judgments and to conform to results from other studies.

The psychological validity of qualitative spatial reasoning in one dimension

One of the central questions of spatial reasoning research is whether the underlying processes are inherently visual, spatial, or logical. We applied the dual task interference paradigm to spatial reasoning problems in one dimension, using Allens interval calculus, in order to make progress towards resolving this argument. Our results indicate that spatial reasoning with interval relations is largely based on the construction and inspection of qualitative spatial representations, or mental models, while no evidence for logical proofs of derivations or the involvement of visual representations and processes was found.

Autobiographisches Gedächtnis: Mentale Repräsentation der individuellen Biographie

Im Rahmen biographischer Methoden stellen autobiographische Berichte, retrospektiv gerichtete Interviews und psychologische Anamnesen wichtige Datenquellen dar. Der wissenschaftliche Wert solcher Informationen wird allerdings sehr unterschiedlich eingeschatzt. So unterstellen manche von vornherein, das Erinnerungen an personlich bedeutsame Ereignisse und Erlebnisse in der Regel unzuganglich oder verfalscht sind; dies ganz in Ubereinstimmung mit dem beruhmten 68. Spruch aus Nietzsches „Jenseits von Gut und Bose“:,,,Das habe ich getan‘, sagt mein Gedachtnis. ,Das kann ich nicht getan haben‘ — sagt mein Stolz und bleibt unerbittlich. Endlich — gibt das Gedachtnis nach“ (Nietzsche o. J., S. 625). Diese Form des Verdrangens als eine spezielle Variante des Vergessens gilt in der Psychoanalyse als zentraler Mechanismus unbewuster psychischer Vorgange (Freud 1915). Zwar weniger radikal, doch nicht minder eindringlich betont auch G. W. Allport, ein besonders engagierter Verfechter der Fallstudienmethode in der Psychologie, das „Biographien, besonders Autobiographien... oft nichts anderes als ein charakterologischer Palimpsest“ sind (1949, S. 399), — also eine immer wieder ubermalte (Gedachtnis-)Inschrift, deren ursprungliche Information uberhaupt nicht oder kaum mehr zu entschlusseln ist. Schlieslich weist Thomae auf „die Bedingungen der Selbstauffassung und Selbsterkenntnis hin, die jede Autobiographie nur zu leicht zum Mittel der Erhohung, Bemitleidung, Rechtfertigung, Verteidigung oder Verklarung des eigenen Selbst werden lassen“ (1985, S.24), fordert aber zugleich die vermehrte Verwendung biographischer Methoden als eines notwendigen Zugangsweges zur Erfassung menschlichen Handelns und Erlebens (vgl. Thomae 1968, S. 106 ff.).

Spatial Reasoning: No Need for Visual Information

One of the central questions of spatial reasoning research is whether the underlying processes are inherently visual or spatial. The article reports a dual-task experiment that was conducted to explore the visual and/or spatial nature of human spatial reasoning. The main tasks were inferences based on a spatial version of the interval calculus introduced by Allen (1983). The secondary tasks were presented visually or acoustically, and were either spatial or non-spatial. The results indicate that spatial reasoning is mainly based on the construction and inspection of spatial layouts, whereas no evidence of the involvement of visual representations and processes was found.

Map use and wayfinding strategies in a multi-building ensemble

This experiment investigated the role of familiarity, map usage and instruction on wayfinding strategies and performance. 32 participants had to find eight goals in a multilevel building ensemble consisting of two distinctive vertical segments. Generally users who were familiar with the building ensemble outperformed first-time visitors of the setting. We tested if the standard wall-mounted floor maps found in the majority of public buildings can help navigation in a complex unknown environment. Unfamiliar users tried to make use of these plans more frequently, but were not able to compensate for spatial knowledge deficits through them. Two strategies of across-level wayfinding are compared with respect to a region-based hierarchical planning approach. Strategy selection relied largely on task and instruction characteristics. Overall, the strategy of moving horizontally into the target section of the building prior to vertical travel was shown to be more effective in this multi-building setting.

Case-Based Reasoning and Model-Based Knowledge Acquisition

This chapter outlines two different yet complementary approaches to enhance cognitive adequacy in the process of knowledge engineering: model-based knowledge acquisition and case-based reasoning. Although both differ with respect to methods, goals and scientific background, arguments are advanced that a linkage of both approaches will result in a significant contribution to the methodology of knowledge acquisition for expert systems. To combine case-based reasoning techniques with conventional rule-based approaches poses the problem of when to use which technique. A conceptual framework for turn taking in problem solving is outlined that involves both heuristics of turn taking and architectural options for knowledge-based systems that impose constraints on turn taking.