Distribution of Cognitive Load in Web Search

TL;DR

This study investigates how cognitive load varies during different stages of web search tasks, introduces a new measurement method, and finds that interface design can reduce mental demands during key search phases.

Contribution

It presents a novel variant of the dual-task method for measuring cognitive load and analyzes its distribution across search task stages, providing insights into cognitive demands during web search.

Findings

Cognitive load is higher during query formulation and document description stages.

Semantic interfaces reduce mental demands during key search phases.

Dynamic cognitive load can be effectively detected within search tasks.

Abstract

The search task and the system both affect the demand on cognitive resources during information search. In some situations, the demands may become too high for a person. This article has a three-fold goal. First, it presents and critiques methods to measure cognitive load. Second, it explores the distribution of load across search task stages. Finally, it seeks to improve our understanding of factors affecting cognitive load levels in information search. To this end, a controlled Web search experiment with forty-eight participants was conducted. Interaction logs were used to segment search tasks semi-automatically into task stages. Cognitive load was assessed using a new variant of the dual-task method. Average cognitive load was found to vary by search task stages. It was significantly higher during query formulation and user description of a relevant document as compared to examining search results and viewing individual documents. Semantic information shown next to the search results lists in one of the studied interfaces was found to decrease mental demands during query formulation and examination of the search results list. These findings demonstrate that changes in dynamic cognitive load can be detected within search tasks. Dynamic assessment of cognitive load is of core interest to information science because it enriches our understanding of cognitive demands imposed on people engaged in the search process by a task and the interactive information retrieval system employed.