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balanced view, presenting positive and negative
aspects. Their review is not conclusive, as they
cannot support their personal opinions with a
scientific evidence, so that the matter remains
unanswered. Moreover, in their review they mix
two different aspects: effectiveness of
videos
as teaching tool
and effectiveness of
recorded
video-lectures
. This confusion is prototypical:
in literature, very often, different aspects get
mixed. Another frequent mistake encountered
in literature is the extension of results obtained
in a given domain to a nearby area, where their
holding may be questionable.
Berner and Adams (2004) conducted a ran-
domized controlled trial to assess the importance
of video+slides as opposed to audio+slides. Ac-
cording to their results, adding video to an audio
presentation does not lead to greater satisfaction
or greater learning.
The German instruction psychologist Glowalla
(2004) expresses a different opinion: according to
him, learners show a better concentration in front
of a video than in a classroom, while the audio +
slide version favours less the concentration, and
is perceived as more boring. Data obtained by
Reisslein et al. (2004) confirm that students felt
that the web-carried video helped them to stay
focused during the instruction. McCrohon et al.
(2001) report that 83% of the students preferred
video streaming to audio streaming. Fey (2002)
argues that video does not increase understanding
or retention, but is favoured by most people due
to emotional reasons.
Moreno and Mayer (2000) state a general prin-
ciple that would bring to the opposite conclusion:
“Students learn better when the instructional mate-
rial does not require them to split their attention
between multiple sources of mutually referring
information”. Their work is sometime used as
an argument against the standard video-lecture
+ slide format, as reported e.g. by Krüger and
Plaza (2005). However, one should be careful
in interpreting Moreno and Mayer's results. In
fact, their experimental work is mostly concerned
with generic multimedia rather than with the
specific case of video-lectures. Krüger and Plaza
extrapolate their results, considering that in video-
lectures there are two areas of the screen, which
are competing for the viewer's attention (the
video and the slide). Hence they conclude that this
leads to the “split-attention effect”. We believe
that this syllogism is misleading. Our argument
is that the video-lecture mimics so closely the
real-world experience (with the lecturer, and an
often large projected slide that is not necessarily
near to the speaker) that students might find this
“spilt” a natural feature, and hence not suffer of
the “split-attention effect”. To ascertain if Krüger
and Plaza are right, or rather if our view is correct,
it would be needed to repeat Moreno & Mayer's
experiments on this particular setting rather than
just extend their results by similarity.
Friedland and Rojas (2008) took the “split-
attention effect” very seriously, up to the point
of building a system that merges the image of
the lecturer taken from the video stream with the
board or slide image, so that the two sources of
information get reunited.
Hermann et al. (2007) attempted to extract
information on users' preferences among the
two formats (audio+slide vs. video+slide) from
the access log files of a system for delivering
audio- and video-lectures, but their evidence is
not conclusive.
We share the opinion that audio and video are
almost equivalent as far as content is concerned
(and moreover it is amazing to observe that in
certain cases the slides are more helpful as a guide
for the speaker than as a support for the listener,
even if we do not question their utility for the
learner in general). The video is however prob-
ably slightly better than audio for a few reasons:
•
Viewing the speaker (at least for a portion
of the lecture) gives a sense of familiar-
ity that helps getting emotionally more
involved;
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