Eye movement in music reading is the scanning of a musical score by a musician's eyes. This usually occurs as the music is read during performance, although musicians sometimes scan music silently to study it. The phenomenon has been studied by researchers from a range of backgrounds, including cognitive psychology and music education. These studies have typically reflected a curiosity among performing musicians about a central process in their craft, and a hope that investigating eye movement might help in the development of more effective methods of training musicians' sight reading skills.
A central aspect of music reading is the sequence of alternating saccades and fixations, as it is for most oculomotor tasks. Saccades are the rapid ‘flicks’ that move the eyes from location to location over a music score. Saccades are separated from each other by fixations, during which the eyes are relatively stationary on the page. It is well established that the perception of visual information occurs almost entirely during fixations and that little if any information is picked up during saccades.e.g., Matin (1974) Fixations comprise about 90% of music reading time, typically averaging 250–400 ms in duration.e.g., Goolsby, 1987; Smith, 1988
Eye movement in music reading is an extremely complex phenomenon that involves a number of unresolved issues in psychology, and which requires intricate experimental conditions to produce meaningful data. Despite some 30 studies in this area over the past 70 years, little is known about the underlying patterns of eye movement in music reading.
Relationship with eye movement in language reading
Eye movement in music reading may at first appear to be similar to that in language reading, since in both activities the eyes move over the page in fixations and saccades, picking up and processing coded meanings. However, it is here that the obvious similarities end. Not only is the coding system of music nonlinguistic; it involves what is apparently a unique combination of features among human activities: a strict and continuous time constraint on an output that is generated by a continuous stream of coded instructions. Even the reading of language aloud, which, like musical performance involves turning coded information into a musculoskeletal response, is relatively free of temporal constraint—the pulse in reading aloud is a fluid, improvised affair compared with its rigid presence in most Western music. It is this uniquely strict temporal requirement in musical performance that has made the observation of eye movement in music reading fraught with more difficulty than that in language reading.
Another critical difference between reading music and reading language is the role of skill. Most people become reasonably efficient at language reading by adulthood, even though almost all language reading is sight reading.Sloboda (1985) By contrast, some musicians regard themselves as poor sight readers of music even after years of study. Thus, the improvement of music sight reading and the differences between skilled and unskilled readers have always been of prime importance to research into eye movement in music reading, whereas research into eye movement in language reading has been more concerned with the development of a unified psychological model of the reading process.Rayner et al. (1990) It is therefore unsurprising that most research into eye movement in music reading has aimed to compare the eye movement patterns of the skilled and the unskilled.
Equipment and related methodology From the start, there were basic problems with eye-tracking equipment. The five earliest studies(Jacobsen 1941; Weaver 1943; Weaver & Nuys 1943; York 1951; and Lang 1961) used photographic techniques. These methods involved either training a continuous beam of visible light onto the eye to produce an unbroken line on photographic paper, or a flashing light to produce a series of white spots on photographic paper at sampling intervals around 25 ms (i.e., 40 samples a second). Because the film rolled through the device vertically, the vertical movement of the eyes in their journey across the page was either unrecordedJacobsen 1941; York 1951; and Lang 1961 or was recorded using a second camera and subsequently combined to provide data on both dimensions, a cumbersome and inaccurate solution.
These systems were sensitive to even small movement of the head or body, which appear to have significantly contaminated the data. Some studies used devices such as a headrest and bite-plate to minimise this contamination, with limited success, and in one case a camera affixed to a motorcycle helmet—weighing nearly 3 kg—which was supported by a system of counterbalancing weights and pulleys attached to the ceiling.Young 1971) In addition to extraneous head movement, researchers faced other physical, bodily problems. The musculoskeletal response required to play a musical instrument involves substantial body movement, usually of the hands, arms and torso. This can upset the delicate balance of tracking equipment and confound the registration of data. Another issue that affects almost all unskilled keyboardists and a considerable proportion of skilled keyboardists is the common tendency to frequently glance down at the hands and back to the score during performance. The disadvantage of this behaviour is that it causes signal dropout in the data every time it occurs, which is sometimes up to several times per bar.Weaver (1943), York (1951) and Young (1971) When participants are prevented from looking down at their hands, typically the quality of their performance is degraded. Rayner & Pollatsek (1997:49) wrote that: "even skilled musicians naturally look at their hands at times. ... [Because] accurate eye movement recording [is generally incompatible with] these head movements ... musicians often need appreciable training with the apparatus before their eye movements can be measured."
Since Lang (1961), all reported studies into eye movement in music reading, aside from Smith (1988), appear to have used infrared tracking technology. However, research into the field has mostly been conducted using less than optimal equipment. This has had a pervasive negative impact on almost all research up until a few recent studies. In summary, the four main equipment problems have been that tracking devices: measured eye movement inaccurately or provided insufficient data; were uncomfortable for participants and therefore risked a reduction in ecological validity; did not allow for the display of records of eye movement in relation to the musical score, or at least made such a display difficult to achieve; and were adversely affected by most participants' tendency to look down at their hands, to move their bodies significantly during performance, and to blink.
Not until recently has eye movement in music reading been investigated with more satisfactory equipment. Kinsler and Carpenter (1995) were able to identify eye position to within 0.25º, that is, the size of the individual musical notes, at intervals of 1 ms. Truitt et al. (1997) used a similarly accurate infrared system capable of displaying a movement window and integrated into a computer-monitored musical keyboard. Waters & Underwood (1998) used a machine with an accuracy of plus or minus one character space and a sampling interval of only 4 ms.
Tempo and data contamination Most research into eye movement in music reading has primarily aimed to compare the eye movement patterns of skilled and unskilled performers.e.g., Weaver (1943), Young (1971), Goolsby (1987) The implicit presumption appears to have been that this might lay the foundation for developing better ways of training musicians. However, there are significant methodological problems in attempting this comparison. Skilled and unskilled performers typically sight read the same passage at different tempos and/or levels of accuracy. At a sufficiently slow tempo, players over a large range of skill-levels are capable of accurate performance, but the skilled will have excess capacity in their perception and processing of the information on the page. There is evidence that excess capacity contaminates eye-movement data with a ‘wandering’ effect, in which the eyes tend to stray from the course of the music. Weaver (1943:15) implied the existence of the wandering effect and its confounding influence, as did Truitt et al. (1997:51), who suspected that at slow tempo their participants' eyes were "hanging around rather than extracting information". The wandering effect is undesirable, because it is an unquantifiable and possibly random distortion of normal eye movement patterns.
Souter (2001:81) claimed that the ideal tempo for observing eye movement is a range lying between one that is not so fast as to produce a significant level of action slips, and one that is not so slow as to produce a significant wandering effect. The skilled and the unskilled have quite different ranges for sight reading the same music. On the other hand, a faster tempo may minimise excess capacity in the skilled, but will tend to induce inaccurate performance in the unskilled; inaccuracies rob us of the only evidence that a performer has processed the information on the page, and the danger cannot be discounted that feedback from action-slips contaminates eye movement data.
Almost all studies have compared temporal variables among participants, chiefly the durations of their fixations and saccades. In these cases, it is self-evident that useful comparisons require consistency in performance tempo and accuracy within and between performances. However, most studies have accommodated their participants’ varied performance ability in the reading of the same stimulus, by allowing them to choose their own tempo or by not strictly controlling that tempo. Theoretically, there is a relatively narrow range, referred to here as the ‘optimal range’, in which capacity matches the task at hand; on either side of this range lie the two problematic tempo ranges within which a performer's capacity is excessive or insufficient, respectively. The location of the boundaries of the optimal range depends on the skill-level of an individual performer and the relative difficulty of reading/performing the stimulus.Souter (2001:80–81)
Thus, unless participants are drawn from a narrow range of skill-levels, their optimal ranges will be mutually exclusive, and observations at a single, controlled tempo will be likely to result in significant contamination of eye movement data. Most studies have sought to compare the skilled and the unskilled in the hope of generating pedagogically useful data; aside from Smith (1988), in which tempo itself was an independent variable, Polanka (1995), who analysed only data from silent preparatory readings, and Souter (2001), who observed only the highly skilled, none has set out to control tempo strictly. Investigators have apparently attempted to overcome the consequences of the fallacy by making compromises, such as (1) exercising little or no control over the tempos at which participants performed in trials, and/or (2) tolerating significant disparity in the level of action slips between skilled and unskilled groups.
This issue is part of the broader tempo/skill/action-slip fallacy, which concerns the relationship between tempo, skill and the level of action slips (performance errors).Souter (2001:80–85) The fallacy is that it is possible to reliably compare the eye movement patterns of skilled and unskilled performers under the same conditions.
Musical complexity