Adaptation to visual and proprioceptive rearrangement: Origin of the differential effectiveness of active and passive movements

In Experiment 1, subjects exposed to a discordance between the visual and ”proprioceptive” locations of external targets were found to exhibit aftereffects when later pointing without sight of their hands at visual targets. Aftereffects occur both when the discordance is introduced in the traditional fashion by displacing the visual locations of targets and when the proprioceptive locations of targets are displaced. These observations indicate that there is nothing unique about the visual rearrangement paradigm—the crucial factor determining whether adaptation will be elicited is the presence of a discordance in the positional information being conveyed over two different sensory modalities. In a second experiment, the effectiveness of active and passive movements in eliciting adaptation was studied using an experimental paradigm in which subjects were exposed to a systematic discordance between the visual and proprioceptive locations of external targets without ever being permitted sight of their hands; a superiority of active movements was observed, just as is usually found in visual rearrangement experiments in which sight of the hand is permitted. Evidence is presented that the failure of passive movements to elicit adaptation is related to a deterioration in accuracy of position sense information during passive limb movement.     

Adaptation to field displacement during head movement unrelated to the constancy of visual direction

Adaptation to vertical field displacements dependent on head turning about a vertical axis was demonstrated under two conditions, rapid training with 100 head movements and 1-h-long training with continuous head turning. The effect of rapid training was measured with the slant estimation method. Adaptation after the longer training was ascertained by comparing the uncertainty ranges for apparent target immobility before and after the adaptation period. Adaptation to field displacements in directions parallel to the plane of the head rotation obtained under corresponding conditions was also measured and found to be somewhat greater than adaptation to vertical field displacements. The result of work by Wallach and Frey that adaptation to field displacement in the direction with the head rotation is greater than to displacement against it was corroborated. While the previous result had, been obtained with rapid adaptation and with the slant estimation method, we confirmed it with 1-h training and by measuring the uncertainty ranges before and after the adaptation period.     

Adaptation to vertical displacement of the visual direction

Sixty Ss wore vertically displacing wedge prisms and adapted by looking at their feet for 10 min. Half of them did this while standing and the others in supine position. The latter condition produced adaptation measurable with a visual-motor test and with a test of egocentric localization, but on a purely motoric test no adaptation was apparent. Standing during the adaptation period produced no effect.     

The effect of experienced limb identity upon adaptation to simulated displacement of the visual field

Ss were confronted with a situation which mimicked the visuomotor consequences of an 11-deg lateral displacement of the visual field (leftward in Experiment I and rightward in Experiment II). The displacement was effected by having E place his own finger to one side of S’s nonvisible finger. Ss who were informed of this deception prior to the exposure period (informed group) manifested significantly less adaptation (“negative aftereffect” and “proprioceptive shift”) than did Ss who were told that their vision would be displaced by the goggles which they were wearing (misinformed group). It was concluded that adaptation to visual rearrangement is strongly influenced by S’s assumptions regarding the adequacy of his vision and the identity of the manual limb which he is viewing.     

Eye movements of highly skilled and average readers: Differential effects of frequency and predictability

This study offers a glimpse of the moment-by-moment processes used by highly skilled and average readers during silent reading. The eye movements of adult readers were monitored while they silently read sentences. Fixation durations and the spatial-temporal patterns of eye movements were examined to see whether the two groups of readers exhibited differential effects of frequency and/or predictability. In Experiment 1, high- and low-frequency target words were embedded in nonconstraining sentence contexts. In Experiment 2, the same participants read high- and low-frequency target words that were either predictable or unpredictable, embedded in highly constraining sentence contexts. Results indicated that when target words appeared in highly constraining sentence contexts, the average readers showed different effects of frequency and predictability from those shown in the highly skilled readers. It appears that reading skill can interact with predictability to affect the word recognition processes used during silent reading.     

Visual tracking of active and passive movements of the hand

Two experiments were performed to evaluate the influence of movement frequency and predictability on visual tracking of the actively and the passively moved hand. Four measures of tracking precision were employed: (a) saccades/cycle, (b) percent of pursuit movement, (c) eye amplitude/arm amplitude, (d) asynchrony of eye and hand at reversal. Active and passive limb movements were tracked with nearly identical accuracy and were always vastly superior to tracking an external visual target undergoing comparable motion. Proprioceptive information about target position appears to provide velocity and position information about target location. Its presence permits the development of central eye-movement programmes that move the eyes in patterns that approximate but do not exactly match, temporally or spatially, the motion of the hand.     

Induced visual movement as nonveridical resolution of displacement ambiguity

Following the proposals made by Kinchla, it is argued that induced movement is a nonveridical resolution of stimulus ambiguity. The ambiguity derives from an identity between displacement of one element relative to another and displacement of the second relative to the first in a featureless field at velocities below the threshold for subject-relative movement. In such conditions, which element actually moves is perceptually unresolvable and veridical judgments therefore accord with chance. When a stationary field is introduced, perception is veridical, but when the field moves with the moving element, perception is nonveridical, i.e., induced movement of the stationary element and induced stationariness of the moving element occurs. The results from three experiments supported this interpretation and showed also that movement velocities above the subject-relative threshold contribute to the resolution of ambiguity.     

Task effects reveal cognitive flexibility responding to frequency and predictability: Evidence from eye movements in reading and proofreading

It is well-known that word frequency and predictability affect processing time. These effects change magnitude across tasks, but studies testing this use tasks with different response types (e.g., lexical decision, naming, and fixation time during reading; Schilling, Rayner, & Chumbley, 1998), preventing direct comparison. Recently, Kaakinen and Hyönä (2010) overcame this problem, comparing fixation times in reading for comprehension and proofreading, showing that the frequency effect was larger in proofreading than in reading. This result could be explained by readers exhibiting substantial cognitive flexibility, and qualitatively changing how they process words in the proofreading task in a way that magnifies effects of word frequency. Alternatively, readers may not change word processing so dramatically, and instead may perform more careful identification generally, increasing the magnitude of many word processing effects (e.g., both frequency and predictability). We tested these possibilities with two experiments: subjects read for comprehension and then proofread for spelling errors (letter transpositions) that produce nonwords (e.g., trcak for track as in Kaakinen & Hyönä) or that produce real but unintended words (e.g., trial for trail) to compare how the task changes these effects. Replicating Kaakinen and Hyönä, frequency effects increased during proofreading. However, predictability effects only increased when integration with the sentence context was necessary to detect errors (i.e., when spelling errors produced words that were inappropriate in the sentence; trial for trail). The results suggest that readers adopt sophisticated word processing strategies to accommodate task demands.     

Reaction time and movement time after active and passive smoking

Reaction time and movement time were studied following active and passive smoking in two groups of 20 women. All subjects were tested under a clean air and smoky air condition and the results showed that, while there was no difference between groups for either measure in the clear air condition, the active smokers had faster reaction time and movement time in the smoky air condition. Smoky air had no significant effect on the responses of the passive smoking group.     

Length,frequency, and predictability effects of words on eye movements in reading

We tested the effects of word length, frequency, and predictability on inspection durations (first fixation, single fixation, gaze duration, and reading time) and inspection probabilities during first‐pass reading (skipped, once, twice) for a corpus of 144 German sentences (1138 words) and a subset of 144 target words uncorrelated in length and frequency, read by 33 young and 32 older adults. For corpus words, length and frequency were reliably related to inspection durations and probabilities, predictability only to inspection probabilities. For first‐pass reading of target words all three effects were reliable for inspection durations and probabilities. Low predictability was strongly related to second‐pass reading. Older adults read slower than young adults and had a higher frequency of regressive movements. The data are to serve as a benchmark for computational models of eye movement control in reading.     

The effect of word frequency, word predictability, and font difficulty on the eye movements of young and older readers

Young adult and older readers' eye movements were recorded as they read sentences containing target words that varied in frequency or predictability. In addition, half of the sentences were printed in a font that was easy to read (Times New Roman) and the other half were printed in a font that was more difficult to read (Old English). Word frequency, word predictability, and font difficulty effects were apparent in the eye movement data of both groups of readers. In the fixation time data, the pattern of results was the same, but the older readers had larger frequency and predictability effects than the younger readers. The older readers skipped words more often than the younger readers (as indicated by their skipping rate on selected target words), but they made more regressions back to the target words and more regressions overall. The E-Z Reader model was used as a platform to evaluate the results, and simulations using the model suggest that lexical processing is slowed in older readers and that, possibly as a result of this, they adopt a more risky reading strategy.     

Eye movements in active visual search: A computable phenomenological model

We present a computational model and corresponding computer simulations that mimic phenomenologically the eye movement trajectories observed in a conjunctive visual search task. The element of randomness is captured in the model through a Monte Carlo selection of a particular eye movement based on its probability, which depends on three factors, adjusted to match to the observed saccade amplitude distribution, forward bias in consecutive saccades, and return rates. Memory is assumed to operate through tagging of objects already recognized as nontargets, which, in turn, requires their processing within the attentional area of conspicuity (AC). That AC is adjusted so that computer simulations optimally reproduce the distribution of the number of saccades, the failure rate for capturing the target, and the return rate to previously inspected locations. For their viability, computer simulations critically depend on memory’s being long-ranged. In turn, the simulations confirm the formation of circulating or spiraling patterns in the observed eye trajectories. We also relate consistently the average number of saccades per trial to the saccade amplitude distribution by modeling analytically the combined roles of the AC in attention and memory. The full Supplemental Appendix A for this article may be downloaded from http:// app.psychonomic-journals.org/content/supplemental.     

Eye movement control in reading and visual search: Effects of word frequency

Eye movements were recorded as subjects either read text or searched through texts for a target word. In the reading task, there was a robust word frequency effect wherein readers looked longer at low-frequency words than at high-frequency words. However, there was no frequency effect in the search task. The results suggest that decisions to move the eyes during reading are made on a different basis than they are during visual search. Implications for current models of eye movement control in reading are discussed.     

The effect of word predictability on the eye movements of Chinese readers

Eye movements of Chinese readers were monitored as they read sentences containing target words whose predictability from the preceding context was high, medium, or low. Readers fixated for less time on high- and medium-predictable target words than on low-predictable target words. They were also more likely to fixate on low-predictable target words than on high- or medium-predictable target words. The results were highly similar to those of a study by Rayner and Well (1996) with English readers and demonstrate that Chinese readers, like readers of English, exploit target word predictability during reading.     

On the relation of adaptation to field displacement during head movements to the constancy of visual direction

When the normal constancy process on which the apparent immobility of the visualfield during head movements is based was strengthened by the same method that produces adaptation to abnormal conditions in the constancy of visual direction, and when this training of the normal constancy process immediately preceded experimental adaptation, the effectiveness of the latter was diminished. This result applied not only to adaptation to horizontal field displacement and to vertical field displacement during turning of the head, but also to vertical field displacement during nodding of the head, a condition to which adaptation was here demonstrated for the first time.     

Adaptation to displaced vision: Amount of optical displacement and practice

The influence of two variables, length of exposure and amount of optical distortion, on adaptation to displaced vision was examined. The extent of adaptation was positively related to number of trials in a task involving spatial localization of a target displaced by a wedge prism. A substantial adaptation (38%) was produced after only two trials. The adaptation was also positively related to degree of optical displacement, except at the highest level used. The findings are discussed in terms of availability of information about the discrepancy between vision and task.     

Development of the third component in prism adaptation: effects of active and passive movement

Adaptation to prismatically displaced vision was assessed using a factorial design involving active or passive exposure movement, active or passive test movement, and target location. Tests of visual shift, ipsilateral and contralateral proprioceptive shift, and ipsilateral and contralateral target-pointing shift were made at the completion of 6, 12, 24, 48, and 96 exposure trials. During the early stages of adaptation (< 48 exposure trials), changes in ipsilateral target pointing were completely accounted for by the sum of the visual and ipsilateral proprioceptive changes. Following longer exposure durations, evidence of a third component was obtained, but only when exposure and test movements were the same (i.e., active-active and passive-passive conditions). The acquisition of such movement-specific response tendencies was interpreted as indicating that the third component represents a change in a central program or schema, which is responsible for guiding a limb to an externally specified location. Target location had no effect on the presence or magnitude of the third component, and there was no indication that the third component transferred intermanually.     

Shifts in kinesthesis through time and after active and passive movement.

The position sense of a stationary arm was investigated subsequent to an horizontally adductive movement with axis the shoulder joint. The right arm was the treated arm: it reached a test position actively, using minimal voluntary effort, or passively from each of 10 starting positons. The blind-folded S localized the index finger of the treated arm by attempting to touch it with the index finger of his left hand. The results indicate that subsequent to active movement the final position of a limb is more accurately known than a position resulting from passive movement. A second finding is that concomitant with both forms of limb placement there is a unidirectional drift of perceived limb position over trials.     

Advantages of rhythmic movements at resonance: minimal active degrees of freedom, minimal noise, and maximal predictability

Using time delay embedding, the authors applied phase space reconstruction to the time series of rhythmic movements of a hand-held pendulum. Subjects (N = 6) produced the manual oscillations about the wrist at the pendulum's resonant frequency and at a higher and a lower frequency. The number of active degrees of freedom required to capture the dynamics of the rhythmic behavior was 3 for the resonant frequency and 4 for each of the nonresonant frequencies. The residual high-dimensional noise was similarly lowest for the resonant frequency. Whereas 33% and 20%, respectively, of the vectors in the phase spaces of the dynamics higher and lower than resonance were unpredictable, only 12% were unpredictable at resonance. Finally, the predictability of the evolving dynamics extended farther into the future for oscillations at the resonant frequency. At resonance, the prediction horizon was 5 times farther than the prediction horizon for the higher than resonance behavior and 2.5 times farther than that for the lower than resonance behavior. The results suggest that, in pendular oscillations of a limb or limb segment, attunement of the central nervous system to the resonant frequency minimizes the variables to be controlled and maximizes the predictability of the rhythmic movement's chaotic dynamics.     

Attention to auditory and peripheral visual stimuli: effects of arousal and predictability

Changes in the distribution of attention among auditory and peripheral visual stimuli were examined in a choice reaction time paradigm. Two variables were manipulated: predictability of stimulus locations and arousal state of subjects. The arousal level of some subjects was raised by occasionally exposing them to brief, mild electric shocks. On most trials either a tone or a light was presented alone (single-stimulus trials). However, on 20% of the trials both a tone and light were presented simultaneously (dual trials). Two dependent variables were used to assess dominance of attention: reaction time (on all trials) and percentage of time each modality was chosen on dual trials. Neither modality was dominant when subjects were in a nonaroused state and stimulus locations were unpredictable. However, peripheral vision dominated when stimulus locations were predictable or when the subjects' level of arousal was raised. The results are discussed with reference to previous research on sensory dominance and on the facilitating or inhibiting effects of auditory stimuli on reaction time.