Experimentation and Modeling: an example journal article
Geoffrey L. Collier and Charles E. Wright
Temporal rescaling of simple and complex ratios in rhythmic
Journal of Experimental Psychology: Human Perception and
Volume 21, No 3, pp 602-627
What do you read anyway?
Science is reported in many places. By the time something makes its
way onto CNN, most of the science has gone. Even textbooks
necessarily only offer established results, not cutting edge work.
Current research is presented mainly in conferences (proceedings),
books (collections of papers) and journals. Each of these forms of
publication is subject to different levels of peer review, of which
journal publication is (should be) the most stringent. The above
article is cutting edge work which directly addresses many of the
questions we are asking in this course. It is tough reading, even for
initiates, so we will be taking it in small doses. You should be able
to get at least the following out of the article:
- Some facts are already known about how humans produce rhythms.
What are the two relevant facts here?
- Models of rhythm production need to account for these (and other)
facts. Which models are considered here?
- What predictions do the models make? What hypotheses do the
- The authors carry out a series of experiments. What are they
trying to show? We will look at Experiment 1 in detail. What do they
tell us about the DESIGN of the experiment? Why is it designed this
- What results do they obtain?
- Do the results address the questions they set themselves
beforehand? Do they help in designing a model?
- What questions remain unanswered?
Structure of a journal article
- Abstract. The quick version.
- Introductory section. Previous work. Hypothesis formation.
- Experimental section. Experimental design and procedure.
- Discussion section. Pulling it all together.
- Maybe, appendices and notes.
- Bibliography. Further reading.
- How is the timing of motor performance controlled?
- In particular, does adherance to natural timing patterns (?)
determine whether the temporal structure (?) of a sequence is
maintained when its overall duration is changed?
Models of rhythm production
There exists a continuum of models, differing mainly in how time is
handeled. Time can be Ordinal (sequence matters), Relative (time
measured with respect to something else) or Absolute (as measured by
clocks of arbitrary precision).
They discuss the Generalized Motor Program with Proprotional Scaling
(GMP/PS) model. This is a relative time model.
Relative durations are prestored, while a single rate parameter
specifies absolute durations at the time of execution.
1) Overall durations can be changed while relative durations remain
constant (proportional scaling, tempo invariance).
2) Relative durations are unconstrained, therefore the model is very
1) Humans do not display perfect proportional rescaling. (This is
mainly a technical point you don't have to worry about. Humans do
pretty good in rescaling simple patterns).
2) Relative durations are completely unconstrained, yet humans have
been shown to prefer some, simple, ratios to other, complex, ratios.
A 2:1 ratio is simple, a 37:17 ratio is very complex.
What is a "natural" temporal pattern?
- Proportional scaling relies on the use of simple ratios.
- Simple ratios can be rescaled (known "fact")
- Complex ratios cannot be rescaled (hypothesis to be tested)
It is known that complex rhythms are harder to produce in the first
place. If they cannot be rescaled, how do we know whether that is
because they cannot be produced properly at any rate, or because they
cannot be rescaled?
Tentative solution: Train subjects for a long time on complex ratios,
and see if their performance is much worse after rescaling.
Experiments and discussion......