Reaction to Zelinsky & Bisley (2015) by Richard Thripp
EXP 6506 Section 0002: Fall 2015 – UCF, Dr. Joseph Schmidt
September 30, 2015 [Week 6]
Zelinsky and Bisley (2015) have presented a literature review regarding visual working memory and priority maps, reaching the conclusion that a vital relationship exists between these concepts, even though researchers often ignore the connection (p. 159). Further, the authors believe priority maps play an integral role in goal-directed behavior, and propose the common source hypothesis: that visual working memory is the foundation for goal prioritization, which is “propagated to all the effector systems” through tailored priority maps for each system, all reaching toward a common goal such as making a cup of tea (pp. 159–160). Priority maps may prevent “interrupts” (distractions) from stealing priority and preventing the goal from being reached.
Zelinsky and Bisley spend a great deal of time talking about the oculomotor system (pp. 156–158). They argue that it and visual working memory provide us with the model for priority maps and that this model generalizes to other visuomotor systems. They discuss evidence of a transformation from retinotopic to motor reference frames as priority maps move from the parietal cortex to the frontal lobe, and predict that a similar transformation will be found for responses in the premotor cortices (pp. 157–158).
The authors seem to have conflated general working memory (“WM”) with visual working memory (“VWM”)—they only refer to WM in regard to the tea-brewing task (p. 160) and argue for the centrality and singular importance of visual working memory throughout their paper. They reach the perhaps regrettable conclusion that all priority maps must have a topographical representation (p. 156). They give agreeable examples involving arm movements (p. 158), saccades (p. 159), and choosing to run right or left (p. 161), while conveniently leaving out discussion of hearing, smell, taste, and touch. Can we not have an auditory or olfactory priority map? Mechanics might listen for particular sounds to diagnose their machines; humans in general may have priority maps for particular smells and tastes to warn them of spoiled or poisonous food. How are these maps topographical? Just because there is a glut of research on vision and visual working memory does not mean that we should simply interpolate such findings to other domains without supporting evidence. Perhaps “priority map” is not the best term, since it is admittedly “by definition, organized into a map of some space” (p. 161). Zelinsky and Bisley seem to want to generalize priority maps to all domains of human attention, and yet the analogy is ill-suited to many of them.
Principally, Baddeley and Hitch’s working memory model and its derivatives focus on the senses that are most salient and important to survival: sight (visuo-spatial sketchpad) and hearing (phonological loop). However, congenitally blind subjects have been found to have significantly better tactile working memory than even semi-blind subjects who were equally fluent in Braille (Cohen, Scherzer, Viau, Voss, & Lepore, 2011). Zelinsky and Bisley (2015) do not even once discuss blindness, nor the possibility of visual working memory’s dominance being experiential in origin. In their defense, congenitally blind subjects have been found to have spatial recognition for Braille reading and to use the same pathways for Braille reading that are typically used for the visual system (Cohen et al., 2010). Nevertheless, the role of experience should always be considered—the priority maps of sighted, congenitally blind, acquired blind, and semi-sighted individuals may have distinct differences. While it is easy to gloss over blind individuals due to their rarity, there may be much to learn from studying blindness. The authors may have benefited from identifying it as an area requiring further research, rather than extrapolating over it.
Cohen et al. (2011) present an intriguing possibility: working memory might have a higher capacity when spread over multiple modalities. Could this allow for several simultaneously operating priority maps? Consider a hunter-gatherer exploring a forest—he or she may have multiple priority maps for sight, hearing, smell, and touch (e.g. wind direction and skin temperature), each contributing to finding food and avoiding danger. It is then apparent that a more fundamental analysis, rather than the technical analysis that Zelinsky and Bisley have provided, may be in order. Not only should experiential sensory history and alternate models be considered, but even the possible evolutionary origins of priority maps.
Cohen, H., Scherzer, P., Viau, R., Voss, P., & Lepore, F. (2011). Working memory for braille is shaped by experience. Communicative & Integrative Biology, 4(2), 227–229. doi:10.4161/cib.4.2.14546
Zelinsky, G. J., & Bisley, J. W. (2015). The what, where, and why of priority maps and their interactions with visual working memory. Annals of the New York Academy of Sciences, 1339, 154–164. doi:10.1111/nyas.12606