Tommy Gärling

ACTIVITY-BASED APPROACHES TO TRAVEL ANALYSIS: CONCEPTUAL FRAMEWORKS, MODELS AND RESEARCH PROBLEMS

Recent policy discussions about information technology in transport and traffic demand management have increased interest in activity‐based approaches to the analysis of travel behaviour, in particular in the modelling of household activity scheduling which is at the core of many of the required changes in travel behaviour. This paper is a state‐of‐the‐art review of conceptualizations and models of activity scheduling with special regard to issues raised by the new policy instruments. In the course of the review, the validity of behavioural assumptions is examined critically and several needs for future research identified.

Cognitive Mapping of Large-Scale Environments: The Interrelationship of Action Plans, Acquisition, and Orientation

A theory about the acquisition and use of cognitive maps of largescale everyday environments is presented. The basic assumptions of the theory are (1) peoples behavior in social and physical environments is determined by action plans, and, if the execution of such action plans requires traveling, plans for how to travel, termed travel plans, are formed and executed; (2) the cognitive maps of large-scale and medium-scale environments acquired are adapted to facilitate movement and travel, and contain information about destinations for travel, spatial information, and travel instructions; (3) cognitive maps are initially acquired in connection with the formation of travel plans and, at the later stages of acquisition, the execution of travel plans (requiring active monitoring) constitutes a more important set of conditions for acquisition. The principles of internal representation of the cognitive map are also discussed.

Environmental Perception and Cognition

Environment and behavior research investigates the mutual relations between the sociophysical environment at all scales and human behavior at all levels of analysis (Moore, 1987). It is generally assumed that there are an “actor,” an external environment or situation, an input from situation to actor resulting in a “psychological response,” and, on the basis of this response, an output from actor to situation termed action (Golledge, 1987). In studies of environmental perception and cognition, the existence of motives, goals, and attitudes toward action alternatives are usually taken for granted, and the psychological responses or processes mediating between the environment and actions are made a primary focus. These processes include the picking up of information from, and about, the environment; the internal, perceptual, and cognitive representation of the information; and judgments, decisions, and choices made on the basis of the represented information. Knowledge gained about perceptual-cognitive processes may improve the quality of human environments through policy, planning, and design, to the extent that it tells how to plan and design environments that do not interfere with the proper functioning of these processes. Examples are the work of Appleyard (1976) and Lynch (1960), resulting in suggested guidelines for how to make cities legible.

The effects of pathway configuration, landmarks and stress on environmental cognition

Abstract The results of this study indicate that manipulations of the pathway grid configuration and landmark placement in a setting cause changes in environmental knowledge. These experimental manipulations were accomplished using a realistic, dynamic simulation technique at the Berkeley Environmental Simulation Laboratory. Measures of environmental knowledge include: memory for incidental information along the simulated urban route, accuracy of route maps, relocation memory for scenes along the route, and questionnaire measures. Data are also presented showing both positive and negative effects of stress from noise on the processes of environmental cognition.

The spatiotemporal sequencing of everyday activities in the large-scale environment

Abstract Choices of where to carry out everyday activities in large-scale environments were conceptualized as a process of forming ‘travel plans’, and, to test a model of how such plans are formed, three experimental simulations of a planning task were performed in the laboratory. In Experiment 1, subjects (high school students) were found to choose a shortest route to travel between a number of actual, familiar locations in a town by first choosing the order between the locations that minimized straight-line (Euclidean) distances, then choosing the shortest paths between the locations in the constrained order. The order choices were, in Experiment 2, found to be made by minimizing distance locally rather than globally, except in some cases when ‘spatial configurations’ of the locations were discovered. Both the results of this experiment and of Experiment 3 suggested that such discoveries were facilitated by a simultaneous representation of the locations which was possible when they were positions on a display, committed to short-term memory or available for perceptual inspection, but to a less extent when they were actual locations.

Memory for the spatial layout of the everyday physical environment: Factors affecting rate of acquisition

Abstract That a memory representation of the spatial layout of a large-scale environment may be acquired very fast was shown in two experiments in which subjects (48 undergraduates and high-school students) were taken on tours through a residential area with which they were unfamiliar. Memory for the path traversed was almost perfect after the first trial, as indicated by almost perfect recall of the order in which a number of designated landmarks had been passed. Memory for the locations of the same landmarks appeared to reach an asymptotic level after the second of three trials. The memory representation of the locations were however not perfectly accurate, thus the asymptotic level might have been an acquisition plateau. The rate of acquisition was slightly faster for subjects driven in a car slowly through the area than for those who walked the same path. Men tended to improve slightly faster than women if they were driven by car but there were no other sex differences. Finally, the acquired memory representation appeared to be resistant to forgetting. Re-learning after a one-week retention interval was faster and rate of learning was not negatively affected whether the trials were massed or distributed with one week in between. The results are discussed in terms of hypotheses concerning the order in which different types of information about spatial layouts (landmarks, paths, and locations) are acquired. The bearing of the results on the question of why memory representations of the spatial layout are often found to be distorted is also discussed.

The role of cognitive maps in spatial decisions

The traveling salesmans problem, in which one decides which order between n locations minimizes total travel distance, was used as a laboratory analogue of spatial decisions in large-scale environments. In an experiment in which university students were observed while solving this problem, a group who received numerical information about distances between locations was found to minimize local distances rather than total distance, that is, to choose first the closest location from the starting location, then the closest location from that chosen, and so forth. However, if a picture of the locations was presented, total distance was minimized more frequently than local distances, presumably because subjects changed their decisions which minimized local distances when they discovered spatial patterns indicating that a shorter path existed. It was also found that a picture did not always have to be presented because subjects mentally constructed a functionally equivalent spatial representation from pieces of direction and distance or only direction information. This finding was even clearer when subjects were allowed to draw pictures of the locations.

Maintenance of orientation during locomotion in unfamiliar environments.

Accuracy of maintenance of orientation during locomotion in unfamiliar environments was investigated by a laboratory procedure in two experiments. In a dark room, subjects were directed to a starting point, shown a target consisting of a point light on the floor, and required to walk straight by following a moving light line (1.18 m/sec) to a stopping point 1.4 to 11.0 m away. From the stopping point, the subjects numerically estimated the direction and distance to the target, which by then was out of sight. In contrast to control conditions with the target visible, the constant and variable errors were larger, and the constant errors varied with locomotion distance in a way that suggested proportional displacements of the target in the same direction as the subjects walked. Forgetting may in part account for the errors, but the main factor was assumed to be accumulated errors in recurrent central processing of the sensory information received about locomotion distance and target location.

Acquisition of different types of locational information in cognitive maps: automatic or effortful processing?

SummaryThe question of whether the acquisition of a cognitive map of a large-scale environment requires central processing of locational information during locomotion was investigated in two experiments. In the first experiment, subjects who were instructed to learn different numbers of spatial relations traversed the same locomotion path one, three or five times. In a subsequent test phase they traversed the path once more, giving numerical estimates of directions and distances to reference points that had been designated along it. The effects of practice and information load indicated that the processing of locational information was effortful. The latencies and the accuracy of the estimates also suggested that the acquisition of information about the directions and crow-flight distances between the reference points required more central information processing than did the acquisition of information about the locomotion path. The amount of central processing capacity allocated to the acquisition of locational information did not, however, seem to be much affected by instructions to learn only a subset of spatial relations. This finding was substantiated by the results of the second experiment in which half of the subjects received no learning instructions.

Distance cognition by taxi drivers and the general public

Twenty-four taxi drivers and an equal number of non-professional or full-time drivers who had been residents of Paris for at least 10 years were requested to estimate straight-line and travel distances, in either distance or time units, between pairs of familiar locations in the city. The results showed that travel distances were invariably estimated as longer than straight-line distances, indicating that the subjects used the knowledge they had acquired of routes. Furthermore, taxi drivers did not make fewer systematic errors than the general public in estimating straight-line distances but they did estimate travel distances as shorter. In support of the view that taxi drivers differ from the general public primarily in procedural knowledge (e.g. of how to drive from A to B) rather than in declarative knowledge (of the straight-line distance between A and B), this finding was interpreted as showing that taxi drivers knew short-cuts to a greater extent than the general public.