Attentional shift by eye gaze requires joint attention: Eye gaze cues are unique to shift attention1

Researchers have demonstrated that attentional shift triggered by gaze direction is reflexive. However, here we show that attentional shift by gaze direction was not always reflexive, but could be modulated by another's perspective. In Experiment 1, a schematic face's line of sight to a peripheral target was obstructed by a vertical barrier located between the face and the target under two conditions. However, the line of sight of the face was clear under another two conditions, in which the barrier was located behind the line of sight by utilizing a depth cue. The gaze cue shifted attention only when the line of sight was not blocked (i.e. joint attention was attained). The arrow cue did not shift attention regardless of the obstruction conditions in Experiment 2. These results suggest that attentional shift by gaze cues, but not arrow cues, involve a higher social cognitive process such as interpretation of the gaze.     

Apparent brightness of a rotating arc-line as a function of speed of rotation

52 Ss were required to adjust the brightness of a center fixation line to equal that of the apparent brightness of an arc line viewed at a distance from the fixation point subtending an angle of 12° to the eye. Adjustments were made when the arc-line was stationary and rotating at speeds of 30, 45, 60 and 75 rpm. It was found that brightness enhancement occurred with increase in speed. This result was interpreted as supporting Ansbacher's account of distortion in the perception of moving arc-lines.     

Reinstating salience effects over time: the influence of stimulus changes on visual selection behavior over a sequence of eye movements

Recently, we showed that salience affects initial saccades only in a static stimulus environment; subsequent saccades were unaffected by salience but, instead, were directed in line with task requirements (Siebold, van Zoest, & Donk, PLoS ONE 6(9): e23552, 2011). Yet multiple studies have shown that people tend to fixate salient regions more often than nonsalient ones when they are looking at images—in particular, when salience is defined by dynamic changes. The goal of the present study was to investigate how oculomotor selection beyond an initial saccade is affected by salience as derived from changing, as opposed to static, stimuli. Observers were presented with displays containing two fixation dots, one target, one distractor, and multiple background elements. They were instructed to fixate on one of the fixation dots and make a speeded eye movement to the target, either directly or preceded by an initial eye movement to the other fixation dot. In Experiment 1, target and distractor differed in orientation contrast relative to the background, such that one was more salient than the other, whereas in Experiments 2 and 3, the orientation contrast between the two elements was identical. Here, salience was implemented by a continuous luminance flicker or by a difference in luminance contrast, respectively, which was presented either simultaneously with display onset or contingent upon the first saccade. The results showed that in all experiments, initial saccades were strongly guided by salience, whereas second saccades were consistently goal directed if the salience manipulation was present from display onset. However, if the flicker or luminance contrast was presented contingent upon the initial saccade, salience effects were reinstated. We argue that salience effects are short-lived but can be reinstated if new information is presented, even when this occurs during an eye movement.     

Eye-tracking the cancellation and focus model for preference judgments

By means of a relatively new eye-tracking method that allows for a test situation much closer to reality, we recorded and examined gaze time and fixation number within the cancellation and focus paradigm, a feature-matching model for preference judgments between two alternatives. In line with the cancellation and focus model we found that when subjects encountered the second option in each pair, shared features were canceled out and thus given less consideration whereas unique features were focused on more. We also investigated the role of feature attractiveness as a second important factor in preference judgments and found a U-shaped relationship between attractiveness and visual consideration intensity; that is, attractive and unattractive features received more attention than did those of intermediate attractiveness. Finally, we tested the ability of two models, Franklin’s rule and the WReSt (Weighted Recalled Stepwise Comparing) heuristic, to predict the preference ratings.     

Interaction of fixation point and stimulus orientation the appearance of rectilinearity

Data from two experiments indicate that the findings of Prytulak (1973) are generalizable to stimulus lines at all orientations: (a) when setting a response dot so that it appears to lie on an imaginary extension of a stimulus line, Ss misplace the dot on the side of the extension opposite the fixation point (a contralateral response, or CR) when the fixation point is in the vicinity of the stimulus line and on the same side of the extension as the fixation point (an ipsflateral response, or IR) when the fixation point is in the vicinity of the response dot; (b) CR is larger than IR; (c) fixation of the stimulus line or any point on its extension produces relatively accurate settings. New findings were: (a) the magnitude of CR decreased as the orientation of the stimulus line approached the vertical or horizontal; (b) the magnitude of CR on or near the horizontal was weaker than on or near the vertical; (c) the magnitude of IR was greater - for stimulus lines lying in the upper half of the visual field than for stimulus lines lying in the lowerhalf. The difficulty - - of accounting for fixation point effects by means of physiological optics was discussed.     

Research on the transition marking between the broken line and solid line of expressway

Drivers often cross the solid line unintentionally during the lane-changing, when the sight distance is blocked by the vehicle ahead. There are significant potential risks to change lanes in solid line area, which would cause traffic flow disruption and traffic safety hazards. If the drivers with limited sight distance can be reminded in advance that the lane marking ahead is a solid line, many drivers will refrain from changing lanes in the restricted area, therefore, it is important to help the drivers with limited sight distance to obtain the information of lane marking ahead. There is limited research on this specific issue presently, nor any relevant regulations or manuals available in China. This paper puts forward a novel concept of transition marking, and a creative approach by adding the transition marking between the broken line and the solid line. The transition marking is considered an information carrier to predict the pass-through right of the road ahead. We have studied the form and length of the transition marking and evaluated its effectiveness through the driving simulation experiment. The form analysis shows that the white mutation broken line has better visibility and legibility. The transition marking length is shown to be closely related to the vehicle speed and distance. The simulation results indicate that the transition marking length is negatively correlated with vehicle distance and positively correlated with speed. Based on the simulation results and detailed statistical analysis, the reference value of transition marking length is proposed. The effectiveness evaluation demonstrates that the transition marking reduces the probability of solid-line crossing during lane-changing dramatically by 92%.     

The effect of fixation point on the appearance of rectilinearity

Data from two experiments indicate that (a) within 3.5 deg visual angle of the fixation point, an eccentrically fixated line and dot appear rectilinear when they are objectively convex toward the fixation point; (b) beyond 3.5 deg, they appear rectilinear when they are objectively concave; (c) the latter effect is not an artifact of the use of stationary fixation points; and (d) the addition of an extraneous line to the stimulus line so as to form a 90-deg angle acts as if to reduce the apparent size of the angle, but does not alter fixation point effects. The data were interpreted as supporting (a) the hypothesis that the stimulus line was more sensitive to illusory distortion than the dot, and (b) the ID (increasing-decreasing) model of the visual field—an inner area of increasing concentric contraction (stimuli appear to lie nearer the fixation point to a degree which increases with distance from the fixation point) is bounded by an outer area of decreasing concentric contraction.     

The visual perception of lines on the road

The present work demonstrates that observers grossly underestimate the length of lines parallel to their line of sight. In Experiment 1, observers, working from memory, estimated the length of a dashed line on the road to be 0.61 m. This result is consistent with observers' using an average visual angle converted to the physical length of visible lines on the road to estimate their length. In Experiment 2, observers gave verbal and matching estimates that significantly underestimated the length of a 3.05-m line on the ground that was parallel to their line of sight. In Experiment 3, observers significantly underestimated the length of dashed lines on the road while in a moving car. The results of Experiments 1 and 3 are described well by Euclidean geometry, whereas the tangle model that utilizes an increasing function of the visual angle to describe perceived extent best describes the results of Experiment 2.     

The corneal reflection technique and the visual preference method: sources of error.

Corneal reflection techniques for eye fixation position measurement have been used in recent years to assess such variables of visual behavior as duration of looking and the area(s) of the stimulus fixated. These techniques are especially useful when measuring visual regard in infants and young children as head restraints are not required. In an earlier article the present authors demonstrated, empirically, that the common assumption that the center of the pupil represents the line of sight is untenable. The present article considers the causes of the errors present in these techniques: it can be shown that theoretical calculations of these sources of error, calculations based both on the anatomy of the eye, and on the optics involved, produce good agreement with their empirically derived magnitudes.     

Differential effects of viewing positions on standard versus semantic Stroop interference

From their finding that the substantial magnitude of the Stroop interference that occurs when a participant’s initial fixation is directed at the optimal viewing position is eliminated when the initial fixation is directed at the end of a word, Perret and Ducrot (2010) concluded that initial fixation at the latter position likely prevents reading. In the present study, we further examined this interpretation. To this end, the two conflict dimensions (semantic vs. response) that were confounded in the original work were separated within a semantically based Stroop paradigm (Neely & Kahan, 2001) that was administered with vocal (instead of manual) responses. In line with past findings showing greater interference in the vocal task, the reported results indicated that standard Stroop interference was reduced, but not eliminated, thus making the initial interpretation in terms of reading suppression unlikely. This conclusion is further strengthened by the presence of isolated semantic interference, the magnitude of which remained significant and was unaffected by viewing position. In sum, these results show that initial fixation of the end of a word simply reduces (nonsemantic) response competition.     

Judging the time to collision with a simulated textured object: Effect of mismatching rate of expansion of object size and of texture element size

We measured the accuracy with which subjects estimated the time to collision with a simulated textured object approaching at constant speed along the line of sight. The independent variable was the ratioR, whereR = (rate of dilation of the texture elements that covered the simulated object) / (rate of dilation of object size). When matching was perfect (i.e.,R = 1.0), the mean of 12 settings was close to the nominal value of 2,000 msec for both subjects. In addition, the standard error of 12 settings was only 25 and 52 msec in 2,000 msec for the 2 subjects. Discrimination threshold for time to collision was not significantly affected byR over the range investigated betweenR = 0 andR = 2.0. However, the accuracy of estimating time to collision was significantly affected byR. Estimated time to collision was a monotonic function ofR. For example, when the mismatch was only 10% (i.e.,R = 0.9) subjects judged time to collision would occur 178 msec later than the true time to collision of 2,000 msec.     

Test of the effect of attention on judged length of a line

Studies to assess experimentally whether attention affects the judged length of a line have produced discordant results. This paper reports the results of a test designed to avoid factors that were not controlled in previous studies. Stimuli were either two vertical lines or two horizontal lines of equal physical length presented briefly on opposite sides of a fixation cross. Subjects were asked to direct their attention to one line when the arm of the cross pointing to the line changed in luminance. This arm was used either as a precue or as a postcue. Subjects judged lines to be longer when a precue preceded the line than when a postcue followed the line.     

Information influences the pattern of eye fixations during sentence comprehension

How does the pattern of eye fixation vary as an informative part of a word is encountered? If the processing of information lags behind the movement of the eyes, then we should expect no variation in the pattern; but if processing is immediate, then the movements of the reader's eyes should correspond to the distribution of information being inspected. An experiment is reported which examined the ways that the text ahead of the point of current fixation can be used to guide the eyes to future fixations, by monitoring fixations during a sentence comprehension task. The patterns of eye fixations upon words with uneven distributions of information (where, for example, words predictable from the sight of their first few letters but not from their last few letters are defined as containing informative beginnings) were observed, and it was found that more and longer fixations were produced when subjects looked at the informative parts of words, particularly at the informative endings of words. The results support the suggestion that eye movements are under the moment-to-moment control of cognitive mechanisms.     

Not fixating at the line of text comes at a cost

Previous research on eye guidance in reading has investigated systematic tendencies with respect to horizontal fixation locations on letters within words and the relationship between fixation location in a word and the duration of the fixation. The present study investigates where readers place their eyes vertically on the line of text and how vertical fixation location is related to fixation duration. Analyses were based on a large corpus of eye movement recordings from single-sentence reading. The vertical preferred viewing location was found to be within the vertical extent of the font, but fixations beyond the vertical boundaries of the text also frequently occurred. Analyzing fixation duration as a function of vertical fixation location revealed a vertical optimal viewing position (vOVP) effect: Fixations were shortest when placed optimally on the line of text, and fixation duration gradually increased for fixations that fell above or below the line of text. The vOVP effect can be explained by the limits of visual resolution along the vertical meridian. It is concluded that vertical and horizontal landing positions in single-sentence reading are associated with differences in fixation durations in opposite ways.     

Compound word effects differ in reading,on-line naming,and delayed naming tasks

Bimorphemic compound words (e.g.,blueberry), bimorphemic suffixed words (e.g.,ceaseless), and monomorphemic controls (e.g.,arthritis) were read in neutral sentence contexts in Experiment 1. The main result revealed longer first fixation durations on compound words than on control and suffixed words. Different effects emerged when naming tasks were used. An on-line naming task revealed substantially shorter naming latencies for compound words than for control and suffixed words. Naming latencies for compound and control words were equivalent in a delayed naming task. These results indicate that on-line naming latencies and word-viewing durations may yield diverging results. They also suggest that activation of constituent words of compound words occurs independently from the specification of conventional word meanings.     

Aspectual Coercion in Eye Movements

Comprehension includes interpreting sentences in terms of aspectual categories such as processes (Harry climbed) and culminations (Harry reached the top). Adding a verbal modifier such as for many years to a culmination coerces its interpretation from one to many culminations. Previous studies have found that coercion increases lexical decision and meaning judgment time, but not eye fixation time. This study recorded eye movements as participants read sentences in which a coercive adverb increased the interpretation of multiple events. Adverbs appeared at the end of a clause and line; the post-adverb region appeared at the beginning of the next line; follow-up questions occasionally asked about aspectual meaning; and clause type varied systematically. Coercive adverbs increased eye fixation time in the post-adverb region and in the adverb and post-adverb regions combined. Factors that influence the appearance of aspectual coercion may include world knowledge, follow-up questions, and the location and ambiguity of adverbs.     

Partly versus Completely Out of Your Mind: Effects of Incubation and Distraction on Resolving Fixation

Incubation has long been proposed as a mechanism in creative problem solving (Wallas, 1926). A new trial‐by‐trial method for observing incubation effects was used to compare the forgetting fixation hypothesis with the conscious work hypothesis. Two experiments examined the effects of incubation on initially unsolved Remote Associates Test (RAT) problems. Following exposure to misleading clues designed to induce initial fixation on RAT problems, versus no clues, participants were retested on problems either immediately after their first attempt (no‐incubation), or after a 40‐second incubation period. Resolution of initially unsolved RAT problems (fixated versus non‐fixated) was examined as a function of complete interruption (Experiment 1) or partial distraction (Experiment 2). An incubation effect, that is, better resolution of initially unsolved problems retested after a delay rather than retesting immediately, was seen only in Experiment 1, in which unsolved problems were completely removed from sight. Furthermore, an incubation effect was found only for initially fixated problems, and not for problems that were not accompanied by misleading clues. The results are consistent with the forgetting fixation hypothesis (Smith & Blankenship, 1989), which states that putting unsolved problems completely out of mind allows initial fixation to dissipate, and the results indicate that the opportunity for some conscious work during incubation periods may not be optimal for resolving fixation.     

Developmental Changes in Pointing as a Function of Attentional Focus

Three experiments investigate the effect of a parent's attentional focus on the pointing of children from 1 to 2 years of age. Children were presented with an interesting sight on one or the other side of a laboratory room while the parent was either looking toward that side or not. The results show that 1-year-olds are more likely to point when the parent is looking at them, whether or not the parent has already seen the interesting sight. In contrast, 2-year-olds tend to point more both when the partner has not seen and when she is no longer looking at the sight than when she is looking at it. These findings are consistent with the idea that when they first start to point, infants use the gesture to enhance the interaction rather than to redirect the attention of the partner. By 2 years of age, children point to redirect attention to an interesting sight and to share attention with a communicative partner.     

Individual differences in fixation duration distributions in reading

The present study investigated the relationship between the location and skew of an individual reader’s fixation duration distribution. The ex-Gaussian distribution was fit to eye fixation data from 153 subjects in five experiments, four previously presented and one new. The τ parameter was entirely uncorrelated with the μ and σ parameters; by contrast, there was a modest positive correlation between these parameters for lexical decision and speeded pronunciation response times. The conclusion that, for fixation durations, the degree of skew is uncorrelated with the location of the distribution’s central tendency was also confirmed nonparametrically, by examining vincentile plots for subgroups of subjects. Finally, the stability of distributional parameters for a given subject was demonstrated to be relatively high. Taken together with previous findings of selective influence on the μ parameter of the fixation duration distribution, the present results suggest that in reading, the location and the skew of the fixation duration distribution may reflect functionally distinct processes. The authors speculate that the skew parameter may specifically reflect the frequency of processing disruption.     

Right visual field advantage in parafoveal processing: Evidence from eye-fixation-related potentials

Readers acquire information outside the current eye fixation. Previous research indicates that having only the fixated word available slows reading, but when the next word is visible, reading is almost as fast as when the whole line is seen. Parafoveal-on-foveal effects are interpreted to reflect that the characteristics of a parafoveal word can influence fixation on a current word. Prior studies also show that words presented to the right visual field (RVF) are processed faster and more accurately than words in the left visual field (LVF). This asymmetry results either from an attentional bias, reading direction, or the cerebral asymmetry of language processing. We used eye-fixation-related potentials (EFRP), a technique that combines eye-tracking and electroencephalography, to investigate visual field differences in parafoveal-on-foveal effects. After a central fixation, a prime word appeared in the middle of the screen together with a parafoveal target that was presented either to the LVF or to the RVF. Both hemifield presentations included three semantic conditions: the words were either semantically associated, non-associated, or the target was a non-word. The participants began reading from the prime and then made a saccade towards the target, subsequently they judged the semantic association. Between 200 and 280 ms from the fixation onset, an occipital P2 EFRP-component differentiated between parafoveal word and non-word stimuli when the parafoveal word appeared in the RVF. The results suggest that the extraction of parafoveal information is affected by attention, which is oriented as a function of reading direction.