RESEARCH METHOD COHEN ok

INTERNET-BASED EXPERIMENTS 239
requested is higher after the experiment has already
been finished’ (Frick et al. 1999:4),i.e.itisbetter
to ask for personal information at the beginning.
Reips (2002a) also advocates the use of ‘warmup’
techniques in Internet-based research in conjunction
with the ‘high hurdle’ technique (see
also Frick et al. 1999). He suggests that most
dropouts occur earlier rather than later in data
collection, or, indeed, at the very beginning (nonparticipation)
and that most such initial dropouts
occur because participants are overloaded with information
early on. Rather, he suggests, it is preferable
to introduce some simple-to-complete items
earlier on to build up an idea of how to respond
to the later items and to try out practice materials.
Frick et al.(1999)reportthatofferingfinancial
incentives may be useful in reducing dropouts, ensuring
that respondents continue an online survey
to completion (up to twice as likely to ensure completion),
and that they may be useful if intrinsic
motivation is insufficient to guarantee completion.
Internet-based experiments
Agrowingfieldinpsychologicalresearchisthe
use of the Internet for experiments (e.g. http://
www.psych.unizh.ch/genpsy/Ulf/Lab/
webExpPsyLab.html). Hewson et al. (2003) classify
these into four principal types:
those that present static printed materials (for
example, printed text or graphics); second are those
that make use of non-printed materials (for example,
video or sound); third are reaction-time experiments;
and fourth are experiments that involve some form
of interpersonal interaction.
(Hewson et al. 2003:48)
The first kind of experiment is akin to a survey in
that it sends formulated material to respondents
(e.g. graphically presented material) by email or
by web page, and the intervention will be to send
different groups different materials. Here all the
cautions and comments that were made about
Internet-based surveys apply, particularly those
problems of download times, different browsers
and platforms. However, the matter of download
time applies more strongly to the second type
of Internet-based experiments that use video
clips or sound, and some software packages will
reproduce higher quality than others, even though
the original that is transmitted is the same for
everyone. This can be addressed by ensuring that
the material runs at its optimum even on the
slowest computer (Hewson et al. 2003: 49) or by
stating the minimum hardware required for the
experiment to be run successfully.
Reaction-time experiments, those that require
very precise timing (e.g. to milliseconds) are
difficult in remote situations, as different platforms
and Internet connection speeds and congestion
on the Internet through having multiple users
at busy times can render standardization virtually
impossible. One solution to this is to have the
experiment downloaded and then run offline
before loading it back onto the computer and
sending it.
The fourth type involves interaction, and is
akin to Internet interviewing (discussed below),
facilitated by chat rooms. However, this is solely
awrittenmediumandsointonation,inflection,
hesitancies, non-verbal cues, extra-linguistic and
paralinguistic factors are ruled out of this medium.
It is, in a sense, incomplete, although the
increasing availability and use of simple screentop
video cameras is mitigating this. Indeed this
latter development renders observational studies
an increasing possibility in the Internet age.
Reips (2002a) reports that in comparison to laboratory
experiments, Internet-based experiments
experienced greater problems of dropout, that the
dropout rate in an Internet experiment was very
varied (from 1 per cent to 87 per cent, and that
dropout could be reduced by offering incentives,
e.g. payments or lottery tickets, bringing a difference
of as much as 31 per cent to dropout rates.
Dropout on Internet-based research was due to
arangeoffactors,forexamplemotivation,how
interesting the experiment was, not least of which
was the non-compulsory nature of the experiment
(in contrast, for example, to the compulsory nature
of experiments undertaken by university student
participants as part of their degree studies). The
discussion of the ‘high hurdle’ technique earlier
is applicable to experiments here. Reips (2002b:
Chapter 10