On the distinction between sensory storage and short-term visual memory

A pattern made by randomly filling cells in a square matrix was presented for 1 see and followed, after various intervals, by an identical or similar pattern. Ss responded “same” or “different.” Performance was fast and accurate if the interval was short and there was no movement or masking of the pattern during the interval. Performance was slower, less accurate, and highly dependent on pattern complexity if the interval exceeded 100 msec or if there was movement or masking. The results are interpreted as evidence for two distinct classes of visual memory: high-capacity sensory storage which is tied to spatial position and is maskable and brief; and schematic short-term visual memory which is not tied to spatial position, which is protected against masking, and which becomes less effective over the first few seconds but not over the first 600 msec.     

Crossmodal change blindness between vision and touch

Change blindness is the name given to people's inability to detect changes introduced between two consecutively-presented scenes when they are separated by a distractor that masks the transients that are typically associated with change. Change blindness has been reported within vision, audition, and touch, but has never before been investigated when successive patterns are presented to different sensory modalities. In the study reported here, we investigated change detection performance when the two to-be-compared stimulus patterns were presented in the same sensory modality (i.e., both visual or both tactile) and when one stimulus pattern was tactile while the other was presented visually or vice versa. The two to-be-compared patterns were presented consecutively, separated by an empty interval, or else separated by a masked interval. In the latter case, the masked interval could either be tactile or visual. The first experiment investigated visual-tactile and tactile-visual change detection performance. The results showed that in the absence of masking, participants detected changes in position accurately, despite the fact that the two to-be-compared displays were presented in different sensory modalities. Furthermore, when a mask was presented between the two to-be-compared displays, crossmodal change blindness was elicited no matter whether the mask was visual or tactile. The results of two further experiments showed that performance was better overall in the unimodal (visual or tactile) conditions than in the crossmodal conditions. These results suggest that certain of the processes underlying change blindness are multisensory in nature. We discuss these findings in relation to recent claims regarding the crossmodal nature of spatial attention.     

Serial position memory in the visual—spatial domain: Reconstructing sequences of unfamiliar faces

In two studies we presented pictures of unfamiliar faces one at a time, then presented the complete set at test and asked for serial reconstruction of the order of presentation. Serial position functions were similar to those found with verbal materials, with considerable primacy and one item recency, position errors that were mainly to the adjacent serial position, a visual similarity effect, and effects of articulatory suppression that did not interact with the serial position effect or with the similarity effect. Serial position effects were found when faces had been seen for as little as 300 ms and after a 6-s retention interval filled with articulatory suppression. Serial position effects found with unfamiliar faces are not based on verbal encoding strategies, and important elements of serial memory may be general across modalities.     

An examination of the relationship between visual capture and prism adaptation

The phenomena of prismatically induced “visual capture” and adaptation of the hand were compared. In Experiment 1, it was demonstrated that when the subject’s hand was transported for him by the experimenter (passive movement) immediately preceding the measure of visual capture, the magnitude of the immediate shift in felt limb position (visual capture) was enhanced relative to when the subject moved the hand himself (active movement). In Experiment 2, where the dependent measure was adaptation of the prism-exposed hand, the opposite effect was produced by the active/passive manipulation. It appears, then, that different processes operate to produce visual capture and adaptation. It was speculated that visual capture represents an immediate weighting of visual over proprioceptive input as a result of the greater precision of vision and/or the subject’s tendency to direct his attention more heavily to this modality. In contrast, prism adaptation is probably a recalibration of felt limb position in the direction of vision, induced by the presence of a registered discordance between visual and proprioceptive inputs.     

Expectancy,controlled attention and automatic attention in prospective temporal judgments

Two experiments indicate that prospective judgments of a temporal target are influenced by nontarget temporal features. The basic task was to reproduce a target interval marked by visual events. In addition, visual or auditory interfering events were delivered. Experiment 1 showed that temporal reproduction is shorter when the interfering events occupy a late rather than early position during the target interval, a result explained in terms of expectancy, which causes attention shifts. This study also revealed that similar trends are obtained whether the interfering event involves a specific task or is irrelevant. Experiment 2 confirmed the position effect, and showed that the duration of an irrelevant cue can influence judgment of the target interval, as if it were also timed without appropriate control.     

Spatial working memory effects in early visual cortex

The present study investigated how spatial working memory recruits early visual cortex. Participants were required to maintain a location in working memory while changes in blood oxygen level dependent (BOLD) signals were measured during the retention interval in which no visual stimulation was present. We show working memory effects during the retention period in early visual cortex which were retinotopically organized in the sense that evoked BOLD responses were specific to the position of the remembered location on an imaginary clock. We demonstrate that this activity is similar to activity observed in conditions in which participants have to direct spatial attention to the same location. We suggest that during the retention interval modulation of neurons coding the remembered location evoke a baseline shift, providing converging evidence for the notion that spatial working memory may use spatial attention as a rehearsal mechanism.     

Temporal changes in visual and acoustic codes in a letter-matching task

The objective of the present experiment was to examine the nature of the coding process in a letter-matching task. Letter pairs that were either visually confusable or acoustically confusable or both visually and acoustically confusable were presented tachistoscopically with a variable interval between the first letter and the comparison letter. The dependent measure was RT for the “different” responses to the three types of confusable items which were each assessed at four interstimulus intervals ranging from 0 to 2 sec. The results indicate that a visual code appears to be emphasized for approximately 1 sec, after which an acoustic code seems to be dominant. There is also evidence which indicates that the acoustic code does not immediately replace the visual code and that both may coexist for a brief period of time.     

Significance of heart rate deceleration in pattern recognition tasks

As strength of foreperiod heart rate (HR) deceleration in reaction time paradigms with a fixed foreperiod has been discussed in terms of activities related to differences in regulations of attentional processes, the present study was concerned with the question of whether this variable also accounts for the variance in the latency of response in two attention-demanding pattern recognition tasks, one of which involved mental rotation. Subjects were required to determine as quickly and as correctly as possible whether a two-dimensional asymmetrical shape was intrinsically identical to a previously presented visual pattern or not, regardless of its rotational position within the picture plane. The first stimulus was always in normal upright position, whereas the probe stimulus could either be rotated or presented in an upright position. The findings of the study are indicative of a reliable relation between anticipatory HR deceleration and reaction time. It was not restricted to detection and response requirements but also held true in the case of additional mental rotation requirements. Strength of anticipatory HR deceleration is therefore interpreted as an indicator of regulations of attentional processes mustered in order to facilitate or to support stimulus detection and response elicitation as well as to prime or to set up the mental structures required in mental rotation. Additional support for this assumption could be found in the analyses of HR changes at the beginning of the response interval.     

Visual sensitivity and mindfulness meditation

Practitioners of the mindfulness form of Buddhist meditation were tested for visual sensitivity before and immediately after a 3-mo. retreat during which they practiced mindfulness meditation for 16 hr. each day. A control group composed of the staff at the retreat center was similarly tested. Visual sensitivity was defined in two ways: by a detection threshold based on the duration of simple light flashes and a discrimination threshold based on the interval between successive simple light flashes. All light flashes were presented tachistoscopically and were of fixed luminance. After the retreat, practitioners could detect shorter single-light flashes and required a shorter interval to differentiate between successive flashes correctly. The control group did not change on either measure. Phenomenological reports indicate that mindfulness practice enables practitioners to become aware of some of the usually preattentive processes involved in visual detection. The results support the statements found in Buddhist texts on meditation concerning the changes in perception encountered during the practice of mindfulness.     

视觉刺激探测的警觉性注意特征初探

采用"预警提示-目标探测"范式,对视觉刺激探测的警觉性注意特征进行初步探索。实验一表明,随着预备到目标刺激的时间间隔(interstimulus interval,ISI)变化,固定位置上探测目标刺激的速度也随之变化,并且对大概率刺激的探测更快,表现出了警觉性注意的稳定性和选择性特征。实验二进一步考察了目标刺激在不同ISI和不同空间位置的情况,除发现与实验一相似的结果以外,被试探测目标刺激的速度随注意视角增大而下降,表现出了警觉性注意的集中性特征。     

Visual habituation at five months: short-term reliability of measures obtained with a new polynomial regression criterion

Using a new polynomial regression criterion, the authors investigated empirically the short-term reliability of infants' visual habituation measures. Twenty-one 5-month-old infants were tested twice with a 1-day interval. Results revealed many reliable habituation measures, a reliable reaction to novelty measure, and a new reliable measure of interest. The 2nd-order polynomial regression criterion probably produced this improvement because it uses all of the available looking time data.     

Distances on hills look farther than distances on flat ground: Evidence from converging measures

Distances on hills are judged as farther than when the same distance is presented on the flat ground. The hypothesized reason for this difference is because perception is influenced by the increased effort required to walk up a hill than to walk the same distance on flat ground. Alternatively, distances presented up a hill might be judged as farther for other, nonperceptual reasons such as bias from demand characteristics. To test whether distances on hills are perceived as farther or are merely judged as farther, we used a variety of measures, including visual matching and blindwalking tasks, and found similar effects across all measures. This convergence is consistent with a perceptual explanation. Second, we mined our data with the goal of making recommendations for future research on this paradigm. Although all of the perceptual measures used showed similar effects, visual matching was the only measure that had good intrasubject reliability. We recommend that future research on this action-specific effect could use any measure unless the research is geared towards individual differences, in which case, only the visual matching measure of perceived distance should be used.     

Attentional and anatomical considerations for the representation of simple stimuli in visual short-term memory: evidence from human electrophysiology

Observers encoded the spatial arrangement of two or three horizontal line segments relative to a square frame presented for 150 ms either in left or right visual field and either above or below the horizontal midline. The target pattern was selected on the basis of colour (red vs. green) from an equivalent distractor pattern in the opposite left–right visual hemifield. After a retention interval of 450 or 650 ms a test pattern was presented at fixation. The task was to decide whether the test was the same as the encoded pattern or different. Selection of the to-be-memorised pattern produced an N2pc response that was not influenced by the number of line segments nor by the length of the retention interval, but that was smaller in amplitude for patterns presented in the upper visual field compared with patterns presented in the lower visual field. A sustained posterior contralateral negativity (SPCN) followed the N2pc. The SPCN was larger for patterns with three line segments than for two, was larger for patterns encoded from lower visual field than from upper visual field, and returned to baseline sooner for the shorter retention interval than for the longer interval. These results, and others, provide an interesting and complex pattern of similarities and differences between the N2pc and SPCN, consistent with the view that N2pc reflects mechanisms of attentional selection whereas the SPCN reflects maintenance in visual short-term memory.     

The role of constant curvature in 2-D contour shape representations

In early cortex, visual information is encoded by retinotopic orientation-selective units. Higher-level representations of abstract properties, such as shape, require encodings that are invariant to changes in size, position, and orientation. Within the domain of open, 2-D contours, we consider how an economical representation that supports viewpoint-invariant shape comparisons can be derived from early encodings. We explore the idea that 2-D contour shapes are encoded as joined segments of constant curvature. We report three experiments in which participants compared sequentially presented 2-D contour shapes comprised of constant curvature (CC) or non-constant curvature (NCC) segments. We show that, when shapes are compared across viewpoint or for a retention interval of 1000 ms, performance is better for CC shapes. Similar recognition performance is observed for both shape types, however, if they are compared at the same viewpoint and the retention interval is reduced to 500 ms. These findings are consistent with a symbolic encoding of 2-D contour shapes into CC parts when the retention intervals over which shapes must be stored exceed the duration of initial, transient, visual representations.     

Visual parsing and priority effects in temporal order judgements of line drawn patterns

Five experiments are reported in which the perception of the order of the components of line drawn patterns presented in rapid temporal sequence on a visual display unit was investigated. In experiments 1 and 2, respectively, a schematic face and an asymmetrical geometric design, and a realistic face and a symmetrical geometric design were each divided into four fragments consisting of outline and three internal features. These fragments were presented to observers in sequences in which the position of the outline in the sequence was systematically varied. Observers reported the perceived order of the fragments. If the order was misperceived the interfragment interval was increased until the sequence was correctly perceived. Analysis of the pattern of perceptual errors and the interfragment presentation interval at which the sequence was correctly perceived indicated that observers tended to perceive the sequence correctly when the outline was presented in first or last position, but had difficulty in doing this when it occupied an intermediate position. This effect was significantly stronger with facial than with geometric patterns. Furthermore, in the case of two face patterns, errors were of a form where observers reported the outline presented in positions two or three as occupying positions one or four respectively. In experiment 3 an identical procedure was used to compare the perception of temporally fragmented normal and inverted faces. The outline position effect was equally strong in both cases. In experiment 4 the relative strength of the tendency to move the outline towards first or final position was assessed by dividing each of two patterns, a face and a house, into three fragments consisting of outline and two groups of internal features. Order perception was significantly better with outline in first or third position, but where it was presented in the intermediate position it was reported as being presented in first position. In experiment 5 the general pattern of results obtained in experiments 1, 2, and 3 was verified with the use of a methodology in which pattern fragment sequences and interfragment intervals were both randomised from trial to trial and the observer's task was to specify the position of the outline in the sequence. Four patterns--a normal face, a face with inverted internal features (INF face), a face outline with irrelevant internal features (IRF face), and a geometric design--were each divided into four fragments consisting of outline and three internal features.(ABSTRACT TRUNCATED AT 400 WORDS)     

Attention maintains mental extrapolation of target position: irrelevant distractors eliminate forward displacement after implied motion

Observers' judgments of the final position of a moving target are typically shifted in the direction of implied motion ("representational momentum"). The role of attention is unclear: visual attention may be necessary to maintain or halt target displacement. When attention was captured by irrelevant distractors presented during the retention interval, forward displacement after implied target motion disappeared, suggesting that attention may be necessary to maintain mental extrapolation of target motion. In a further corroborative experiment, the deployment of attention was measured after a sequence of implied motion, and faster responses were observed to stimuli appearing in the direction of motion. Thus, attention may guide the mental extrapolation of target motion. Additionally, eye movements were measured during stimulus presentation and retention interval. The results showed that forward displacement with implied motion does not depend on eye movements. Differences between implied and smooth motion are discussed with respect to recent neurophysiological findings.     

Measuring the size of mental images

Mental images seem to have a size; the experimental problem was to map that image size onto a scale of physical measurement. To this end, two experiments were conducted to measure the size of mental images in degrees of visual angle. In Experiment 1, college students employed light pointers to indicate the horizontal extent of projected mental images of words (the letter string, not the referent). Imagined words covered about 1.0 degress of visual angle per letter. In Experiment 2, a more objective eye-movement response was used to measure the visual angle size of imagined letter strings. Visual angle of eye movement was found to increase regularly as the letter distance between the fixation point and a probed letter position increased. Each letter occupied about 2.5 degrees of visual angle for the four-letter strings in the control/default size condition. Possible relations between eye movements and images are discussed.     

A primacy effect in monkeys when list position is relevant

In Experiment 1 (1a and 1b), Rhesus monkeys (Macaca mulatta) learned lists of two-choice visual discriminations in which list position was relevant to discrimination performance. For example, Stimulus A was the rewarded stimulus if it was presented at List Position 1, but was not rewarded if it was presented at any other position in the list; similarly, Stimulus B was rewarded only at List Position 2, and so on. In learning these lists, all animals showed a marked primacy effect. In Experiment 2 (2a and 2b), Rhesus monkeys and Cynomolgus monkeys (M. fascicularis) learned lists of visual discriminations in which each visual stimulus occupied a fixed position in a list, but list position was not relevant to discrimination performance. For example, Stimulus E was always rewarded, and was always presented at List Position 1. To increase the salience of list beginning as a distinctive event, successive presentations of the list were separated by 24-hr intervals. In Experiment 2 there was no primacy effect, however. These results show for the first time that a primacy effect can be obtained in visual discrimination learning by monkeys. Furthermore, they suggest that it is obtained only when list position is relevant to the discrimination learning task.     

Temporal and spatial features in detecting one- and two-dimensional constraints in complementary visual displays

Spatial complements of visual displays of one- and two-dimensional Markov spatial constraints were successively presented for discrimination. Although each complement alone was sufficient for discrimination, spatial complements interfere when presented successively in time. Substantial changes in performance are observed for temporal separations as short as 10 msec and for spatial separations as short as 1 min in visual angle. Complete processing appears to take place in the interval between successive displays: thresholds are constant for a constant sum of display duration plus the interfield interval. Implications of complementary interference for a general theory of visual masking are briefly discussed.     

The storage of physical and name properties in short-term visual memory

Two experiments investigated the hypothesis that short-term visual memory is based primarily on physical features of the visual input. Subjects were required to recall visually presented figures or the names of those figures presented either visually or aurally at a number of different retention intervals. Subjects shadowed words during the retention interval presented aurally in Experiment I and visually in Experiment II. In both experiments, figures were recalled better than names and no differences in recall of names were found due to presentation modality. Recall of both names conditions showed a steady decline across retention intervals whereas recall of figures remained at a relatively high level. These findings were interpreted as providing further support for the existence of short-term visual memory not subject to auditory recoding and based primarily on physical features of the input. It was suggested that such visual memory is limited in capacity so that input exceeding this capacity is recoded into an auditory-verbal-linguistic form.