relevance and those of interest from a spatial behavior perspective is described below. Perhaps the most important dimensions are time and space, but many others warrant the attention of researchers as well. For convenience, in discussing the various interactions between ICT and activities, we refer to changes within the leisure activities category (substitution or complementarity) as intra-category interactions while changes between leisure and other categories (work and maintenance) are called inter-category interactions.
From the diverse list of dimensions available to classify leisure activities, the following discussion focuses on 13 that seem to us to be the most ICT “sensitive” (Doherty, 2003 uses some of these same dimensions to characterize any type of activity). As a way of organizing the discussion, these dimensions are grouped into five types: location, time, social context, traits intrinsic to the activity, and the benefit/cost tradeoff. Accompanying the description of the 13 dimensions, Table 3 summarizes the relationships between the four types of ICT interactions introduced in Section 3.1, and each of the dimensions. Although some blank cells of Table 3 could be filled in, those relationships seem less likely and/or less important than the ones that are included.

Location: An activity is inseparable from its time and space dimensions. Location and time
have long been recognized as the basic attributes of each activity. The introduction of ICT has
changed the meaning or the costs of traversing space in time, but has not nullified them! Thus,
our first group of dimensions of leisure activities refers to the impacts of ICT on the location of activities.

1. Location (in)dependence: A location, in the present context, is not just the geographical
coordinates at which the activity takes place. An additional location-relevant attribute includes the type of setting, such as outdoor-indoor or home-other (Lawson, 2001). As discussed earlier in connection with Figure 1, ICT facilitates the engagement in some leisure activities at any location. Listening to a radio program can be done almost anywhere, subject to some coverage limitations. Enjoying the sunny beach while still “communicateable” with a cellular telephone is another example. But there are still a number of constraints acting to limit spatial independence. Many leisure activities require particular types of facilities (an auditorium, a ball field, a beach), and others are focused on a specific geographic location of interest (one’s backyard garden, the Alps, the Taj Mahal). Thus, the expansion of the spatial dimension of the choice set is not universally continuous.

2. Mobility-based vs. stationary: Leisure activities, as noted above, may be locationspecific
or independent of place. But a separate dimension refers to the question of whether the activity itself involves movement or is performed at a given location (see, e.g., Mokhtarian and Salomon, 2001 for a conceptual analysis, and Bhat and Lockwood, 2003 for a recent empirical study, that make this distinction). Driving, biking, and hiking as well as flying and boating are all examples of movement that can be leisure-related, at least in part. To the extent that movement is an essential component of the activity, clearly the ability to replace it with an ICT alternative is quite limited. At the margin there may be opportunities, however, such as using virtual reality technology for pilot training or sports training courses (see, e.g., Kernan and Domzal, 2000).

Time, the second fundamental attribute of activities, has two aspects. The first is the timing of
activities on the calendar (relating to dimensions 3 and 4), and the second is the duration of the
activity (dimensions 5 and 6). ICT may affect both.

3. Time (in)dependence: Similar to the case of spatial independence, ICTs relieve a
number of temporal constraints, thus allowing much flexibility in the timing of activities.
The primary effect of ICT is that it facilitates the disengagement of activities (e.g., theatre, sports events, etc.) from a fixed time constraint. Asynchronous leisure-related communications with others (e.g., e-mailing friends) is another example of the relaxation of coordination constraints. With regard to the temporal dimension, this expansion is, where applicable, generally continuous (from a technological standpoint, although still limited by individuals’ other constraints), thus increasing the flexibility of timing activities. However, the qualifier “where applicable” is important: many more sports, cultural, and entertainment events are not televised (or otherwise digitally captured for anytime playback) than are. And as noted earlier, even when an ICT alternative is available, it may not be a satisfactory substitute.

4. Planning horizon: For most people, activities are planned ahead of time and only a few
activities result from impulsive behavior. The planning of activities can be short, medium or long term, where we use “medium” to refer to activities that are planned for some days or months (e.g., going to Antarctica next year), and “long” to mean over a number of years, e.g., a long-term commitment to work. At the other end, the short-term activity planning horizon refers to hours (e.g., going to eat out tonight). ICT is likely to affect leisure activities having each of the various planning horizons. With respect to the short term, ICT facilitates greater time-space flexibility, so planning and engagement in activities can be on impulse, with almost zero planning horizon. At the other extreme, ICT may make it easier for even the most committed workaholic to plan more and/or longer holidays, with the assurance that she can still make the necessary business contacts while away from the office. This may result in an increase in the demand for vacation travel.

5. Temporal structure and fragmentation: As discussed in Section 2.1.2, ICT changes
not only the timing constraints but also the structure of the blocks of time required for performing certain activities. For example, some home-based alternatives to a movie (VCR and DVD, but not television) allow the fragmentation of the time block devoted to that activity, in contrast to the case of a movie theatre where an uninterrupted block of time must be allocated. (In fact, the last sentence should be qualified, as increasingly interruptions do occur at the theatre, a facility that is presently being invaded by cellular phones. In this case, ICT can be seen as a potentially undesired intrusion on, as well as a facilitator of, leisure).

6. Possible multitasking: As mentioned in Section 2.1.3, some leisure activities are amenable to multitasking, both in the intra- and inter-category dimensions. Reading a book or jogging while listening to music are simple examples of intra-leisure multitasking, while watching television and watching the kids simultaneously falls into the inter-category case. In the case of multitasking it is important to note the nature of the relationship between the two or more activities simultaneously undertaken by the individual. In some cases the tasks may be conflicting in the sense that the gratification from one activity is reduced due to the attention consumed by the other. This relationship seems likely to occur more often in the inter-category interactions. In other cases, the activities may complement each other in gratification. Again, ICT can enable multitasking, but not all multitasking may require ICT. Among the new ICTs, the cellular telephone is especially susceptible to multitasking (both incoming and outgoing calls are frequently placed while doing something else, often traveling), but old ICTs such as TV and radio have also been associated with considerable multitasking.

The Social Context of leisure activities is yet another major attribute that calls for attention. The implications of the dimensions related to the social context may include issues like the need for coordination, the positive or negative utility of spending time with particular individuals, and the extent to which an individual wants to be “on display” in conducting an activity. Again, it is worth emphasizing that the attributes of the activity as defined by the researcher may not necessarily be the same as perceived by the individual.

7. Solitary vs. social activity: While some leisure pursuits may be enjoyable only in solitude (e.g., reading a book, contemplating) and others can only be gratifying in a group (e.g., playing soccer), there are a variety of activities in which engagement can be either solitary or social. The category of “other people” can be completely redefined by ICT; i.e. ICTs enable the relaxation of the boundary between the two types of activities.
Stand-alone computer-based games, such as chess and many other games, involve a virtual partner or group that is personified by the computer. Alternatively, networked computers facilitate the formation of a group consisting of real people who may be scattered around the globe. But these may differ between a group of people who “meet” repetitively and thus share some level of belongingness, or a random group, typified by a single event interaction. One potential impact of ICT is that some individuals with solitary leanings may now opt for an ICT-based activity that is locally solitary but virtually networked.

8. Active vs. passive participation: If “active” and “passive” are opposites as they are commonly taken to be, then a “passive activity” is something of an oxymoron. Taken to an extreme, of course, the only time we are fully passive is when we are dead. We believe it is useful to distinguish, however, the degree of agency or instrumentality of the individual in an activity. Here, therefore, we do not use “active” to refer purely to physical involvement or to movement, but rather to “engagement in an activity (whether physical or mental) in a way that affects the outcome”. Thus, playing in a baseball game is clearly active participation, watching it on TV is clearly passive, and watching it a stadium is somewhat less passive, given that the collective reaction of the spectators can encourage or discourage the athletes on the field 20 (with the same distinctions applying to mental activities such as a bridge tournament). There is an interaction between this dimension and the following one: for physical activities (consider performance in musical, theatrical, or athletic events), if the individual wishes to be an active participant, ICT is not likely to offer an attractive substitute (although ICT can disseminate the resulting physical activity more broadly), whereas mental activities offer more opportunities in this regard (as discussed under dimension 7 above).

Traits Intrinsic to the Activity: Several characteristics of the activity itself are relevant to the potential impacts of ICT, including whether it is predominantly physical or mental (or both, or neither), the technology or equipment required to conduct the activity, and the degree of formality of arrangements required.

9. Physical vs. predominantly mental: Leisure activities vary widely with respect to the
nature of the activity performed, from strenuous physical activity to predominantly mental activity, or even the lack of either, as in the case of getting tanned on the beach 21.
Mental activities are presumably the most amenable to the ICT substitution effects of category 1 (e.g. playing chess or backgammon either with the computer, or with a remote human opponent over the Internet), and may constitute the bulk of the displacing ICT activities of category 2. However, even physical activities can be (a) crowded out by new ICT-based interests (category 2); (b) newly inserted into one’s schedule because of time made available by ICT (e.g., going to the health club during the saved commute time due to telecommuting; category 3), or (c) facilitated by ICT (e.g. using the mobile phone to organize an impromptu tennis game; category 4).

10. Equipment/media (in)dependence: Many leisure activities involve the deployment of
physical objects of some kind, whether equipment (such as a basketball and hoop, tennis racket and net, camping gear, camera), a vehicle (boat, horse, bicycle, surfboard, recreational vehicle), or other physical media (e.g. cooking ingredients, craft materials, collectibles such as stamps or coins). In some cases, of course, the equipment in question is an ICT. To the extent that physical objects (other than ICT) are required, it is unlikely that a suitable ICT-based substitute (category 1) can be found (although there are limited exceptions relating to physical objects that primarily convey information that can be digitized, as in the potential replacement of physical books with electronic ones, or in the replacement of film and developing equipment with digital photography storage and display media. Even in these cases, however, physical equipment is required, albeit ICT equipment). However (category 4), ICT can certainly facilitate planning such activities (possibly leading to greater participation than would have been the case otherwise, as when one joins a special interest group, finds people of similar interests, and then joins them for an activity), and may augment participation in them with additional information not readily available otherwise (e.g. finding recipes and cooking instructions on the Internet).
In other cases (e.g. watching a ball game), the activity itself does not necessarily require any special equipment, and it is generally a subset of this set of cases that can be considered potentially substitutable by ICT. In these cases of potential substitutability, the utility of the ICT alternative, and hence the choice between the traditional and ICTbased forms of the activity, will very much depend on the technological characteristics of the ICT alternative (assuming its availability): Does it transmit audio, still pictures, fullmotion video? Is it one-to-one, one-to-many, or many-to-many? Is it synchronous or asynchronous? Can access be mobile, or only fixed? Is the desired/needed amount of transmission bandwidth available? What is the comparative cost of the ICT alternative (discussed under dimension 13 below), and is it shared or transferred (e.g. by using the employer’s high-speed network to browse the Internet)? Beyond these technical characteristics lie the more intangible factors that we have mentioned earlier as being relevant to choice: the degree to which the ICT alternative replicates the experience of “being there” to the desired extent.

11. Informal vs. formal arrangements required: Some leisure activities require formal
arrangements prior to engagement, such as purchasing tickets, owning a subscription, or
simply coordinating for a particular service, such as in a spa. ICT will generally ease the
process of making the necessary arrangements. In particular, it is the telephone (fixed as
well as mobile) and the computer that enable these arrangement. It is worth noting that
for ICT to be an efficient enabler of formal arrangements, there need to be payment
mechanisms, namely credit options, so that the benefits of ICT can be realized.

Benefits and Costs: Whether consciously or unconsciously, human decisions other than the most primally instinctive ones tend to involve some kind of mental tradeoff between costs and benefits.
The perceived benefits constitute the motivation or drive to take part in leisure and other
activities. This motivation serves as a mechanism that encourages engagement in activities as
long as the gratification is greater than the costs involved. The remaining two leisure activity
classification dimensions explore these two aspects.

12. Motivation: It is useful to determine the motivations for engaging in a given leisure activity, because these motivations are likely to affect the gratification one gains from the ICT-based, as opposed to the traditional, form of an activity. It is plausible to assume, for example, that playing a game on a stand-alone computer provides at least different, if not less, gratification than that experienced in playing the same or similar game with other real people through a network (and for that matter, also from playing with others on a non-networked computer). As distinguished from the empirically-driven classification of Tinsley and Eldredge (1995) shown in Table 1 (which has some unexpected groupings, such as placing chess in the Creativity group with baking, and separate from other games in the [mental] Competition group), we suggest that the motivations for conducting a given leisure activity can include one or more of the following six conceptual types:

• physical exercise (as active participant or passive spectator, where the latter refers, e.g., to the motivation of enjoying watching the skilled execution of physical activities by others);
• mental exercise, learning (as participant or spectator);
• aesthetic or creative production (participant, spectator);
• socializing;
• status or self-identity enhancement (e.g., Kernan and Domzal, 2000);
• relaxation, escape.

For each of these types (with the possible exception of the last one), the motivation can further be one of enjoyment, or of necessity/expectation (the last category seems to require an enjoyment motive – almost by definition, if one relaxes because of an activity, one is enjoying it). In the former case (enjoyment motive), the leisure activity is valued as an end in itself; in the latter case (necessity motive) as a means to the end of fulfilling a duty or satisfying an expectation. For example, one may visit the in-laws because the spouse demands it, or one may engage in “recreational” jogging because one is determined to stay in shape rather than out of an intrinsic enjoyment of the activity.
There are, as usual, hybrid cases, relating to the reason for the blurry boundary between activity classes discussed in Section 2.1.1. Consider for example the case in which an individual is expected to play golf with a business client. This is purely a work-related activity if the individual does not enjoy the game. But if the person actively likes golf and plays it “on her own time” as well as in the work context, this requirement of the job may actually make work more like leisure (unless playing a client involves sufficient stress so as to rob an otherwise desired activity of its pleasure).

13. Costs of various types are yet another dimension along which the engagement in leisure
activities may vary. Generalized costs, including monetary, time, physical energy and others affect the level of engagement in activities. Costs are a disutility and are compared against other dimensions, most prominent of which are the motivations. Costs act as constraints on particular leisure activities; expensive activities cannot be included in one’s choice set if the individual’s budget does not allow for it. But, there may be a trade-off not only between different activities, but also between participation levels in a particular activity. One may go to a concert less frequently than desired but still budget for concerts rather than other activities. As frequently mentioned earlier, one important effect of ICT on this dimension is that of reducing costs, as better coordination and scheduling are facilitated. But the costs of acquiring and using the ICTs themselves must not be neglected. In particular, computer-based leisure activities can be quite costly in terms of maintaining state-of-the-art hardware and software, along with communications costs – especially if users become “addicted”.

In summary, most dimensions identified above can be categorized as being ICT-sensitive, meaning that the introduction of ICTs may have significant impacts on the way people perceive leisure activity options and use. The two most directly relevant attributes from a travel behavior perspective are the impacts on time and space, but all are relevant to travel to the extent that they influence the adoption of ICT activities, which in turn have travel implications.

20 Not to mention the occasions on which a fan has actually directly changed the outcome of a game, e.g. by interfering with a ball that a player could have caught.
21 Of course, even mental activities require at least a modicum of physical movement, and most physical activities require strategic and tactical mental engagement. Thus, “physical” does not preclude mental activity, but we use the label “predominantly mental” to distinguish those activities which involve mental engagement without much physical movement.