There and back again: Memory, eye movements, and psychophysics on three continents

Abstract

In “The development of retro-cue benefits with extensive practice” I demonstrated that retrospectively cueing short-term memory representations is unlikely to reflect the process of bringing implicit memory representations (i.e., iconic or fragile memory) into stable and reportable working memory. Instead, retro-cues shift memory resources within the same memory system (working memory). As a result, participants are able to report even those representations that were initially weakly encoded and would not have survived the recall process without first being prioritized via the retro-cue. These findings also imply that estimates of working memory capacity represent the measurement of a construct defined by the employed paradigm, rather than being pure measure of a cognitive capacity. The true capacity of human working memory is therefore still unknown.

In “Successful visually guided eye movements following sight restoration after congenital cataracts” I investigated basic visually-guided eye movements in individuals who were born blind (unable to perceive any patterned visual input) due to congenital bilateral total cataracts, and who received a sight-restoring cataract operation later in life. I revealed that these individuals were able to make goal-directed eye movements despite an absence of vision during the critical first year of their lives. They presented with severe clinical nystagmus (like most individuals with uncorrected early-life visual deficits) but were not worse at making eye movements towards visual targets than a control group with similar nystagmus, including saccades. This was good news for such cataract patients as eye movements are one of the most fundamental elements of human vision. My results imply that even without vision during the early-life sensitive phase, the saccadic eye movement system could still develop later in life, when vision was restored. In addition, I developed a method for calibrating eye trackers in any individual with nystagmus or other eye movement disorders that prevent stable target fixation. This algorithm opens up the way for research into visually guided eye movement dynamics in individuals with severe nystagmus, including sight-recovered cataract individuals. Research in this area has so mostly far been limited to the dynamics of the nystagmus waveform without mapping eye position to screen coordinates.

In “Serial dependence reflects integration of task-relevant information in working memory” I discovered that it is not only previously observed visual information that influences current perception and behavioural responses, but that all information concurrently represented in working memory influences behavioural responses to individual percepts. That is, responses were biased toward similar and task-relevant information (indicating integration) and biased away from dissimilar and task-irrelevant information (indicating repulsion). These results revealed the crucial role of working memory in visual history effects (such as serial dependence), a field of research that has received increased interest in recent years. We propose that, similar to multisensory perception, several observations of the same object could be integrated to increase the reliability of an object representation based on a single instance of perception, in order to facilitate more effective object-oriented behaviour.