The dynamics of operations in visual memory: a review and new evidence for oscillatory priming

Evidence from neurophysiological studies indicates that the synchronization of distributed neuronal assemblies in the gamma frequency range is responsible for the integration of discrete stimulus components into coherent wholes (e.g., see Singer, 1999 for review). Psychophysical support for this hypothesis has been reported in experiments that demonstrate that the presentation of a synchronous-premask frame within a 40-Hz flickering premask matrix primes the subsequent detection of a target Kanizsa-type square by generation of a 40-Hz prime (Elliott & Müller, 1998). Psychopharmacological and electrophysiological evidence suggests that this priming mechanism is related to activity in interneuronal networks and relies on the combined function of prefrontal and posterior circuits. In addition, psychophysical experiments demonstrate the existence of a prime-specific visual short-term memory that oscillates at 40 Hz and remains functional for up to 300 ms post-stimulus offset. These results are consistent with a view of the prime as a form of oscillatory mechanism, related to the persistence of visual information (Coltheart, 1980) and in the capacity guided by (prefrontal) top-down influences upon visual-cortical function.     

Evidence for 40-Hz oscillatory short-term visual memory revealed by human reaction-time measurements

Four experiments show that presentation of a synchronous premask frame within a 40-Hz, flickering premask matrix primes subsequent detection of a Kanizsa-type square by generation of a 40-Hz prime. Reaction time (RT) priming effects indicated a 150-200-ms prime duration following premask display. RTs were also found to be sensitive to the phase relationship between offset of the premask display relative to the onset time of the target: Priming effects were maximal when the target was presented out of phase with premask presentation (i.e., at interstimulus intervals displaced by 180 degrees relative to the 40-Hz rhythm of premask-frame presentation). Taken together, these results demonstrate the existence of a very short-term visual memory that oscillates at 40 Hz. The findings are discussed in the context of complementary psychological and neurophysiological findings related to visual-object coding and the role of gamma-band activity in the brain.     

Ready-signal effects as a function of experimental design in simple reaction time

In the between-S design, 20 Ss had a visual ready signal presented on each trial; for another 20 Ss, the ready signal was always absent. The within-S design consisted of 40 Ss that experienced both ready-signal conditions in semirandom order. Two intensities of a 1,000-Hz tone were used as the response signals Ready-signal manipulation had pronounced effects under the within-S but not the between-S design irrespective of response-signal intensity     

跨通道语义启动对视觉注意的影响

采用生活中的真实客体,考察了跨通道语义相关性对视觉注意的影响以及跨通道促进的时程。结合启动范式和点探测范式,实验1发现在听觉启动600ms后,被试对高相关视觉刺激的反应比对低相关刺激的反应更快,而在视觉启动下没有发现启动效应。实验2发现在启动刺激呈现900ms后跨通道启动效应消失。研究证明了基于先前经验的视、听语义相关能够促进视觉的选择性注意。     

The slippery context effect in psychophysics: Intensive,extensive, and qualitative continua

When subjects gave magnitude estimates of 500- and 2500-Hz tones at various SPLs, they judged a 500-Hz tone of 60 dB to be as loud as a 2500-Hz tone of 57 dB in one context (low SPLs at 500 Hz, high SPLs at 2500 Hz), but as loud as a 2500-Hz tone at 40 dB in another context (high SPLs at 500 Hz, low at 2500 Hz) (Marks, 1988). Such shifts in matches derived from judgments of multi-dimensionally varying stimuli are termedslippery context effects. The present set of seven experiments showed that slippery effects were absent from judgments of pitch of tones at different loudnesses, duration of tones at different pitches, and length of lines at different colors, though a small effect emerged in judgments of duration of tones and lights. Slippery context effects were substantial when subjects gave magnitude estimates of loudness of 500- and 2500-Hz tones under conditions in which the pitch at each trial either was cued visually beforehand or could be known through the regular stimulus sequence, and with instructions to make absolute magnitude estimates. The results are consistent with the view that slippery context effects occur automatically and “preattentively.”     

The slippery context effect in psychophysics: intensive, extensive, and qualitative continua.

When subjects gave magnitude estimates of 500- and 2500-Hz tones at various SPLs, they judged a 500-Hz tone of 60 dB to be as loud as a 2500-Hz tone of 57 dB in one context (low SPLs at 500 Hz, high SPLs at 2500 Hz), but as loud as a 2500-Hz tone at 40 dB in another context (high SPLs at 500 Hz, low at 2500 Hz) (Marks, 1988). Such shifts in matches derived from judgments of multidimensionally varying stimuli are termed slippery context effects. The present set of seven experiments showed that slippery effects were absent from judgments of pitch of tones at different loudnesses, duration of tones at different pitches, and length of lines at different colors, though a small effect emerged in judgments of duration of tones and lights. Slippery context effects were substantial when subjects gave magnitude estimates of loudness of 500- and 2500-Hz tones under conditions in which the pitch at each trial either was cued visually beforehand or could be known through the regular stimulus sequence, and with instructions to make absolute magnitude estimates. The results are consistent with the view that slippery context effects occur automatically and "preattentively."     

Effect of stimulus pulse duration and interstimulus interval on cross-modal matching of auditory and lingual vibrotactile stimuli

Cross-modal matching functions for eight intensity levels of a 1000-Hz auditory stimulus and a 250-Hz lingual vibrotactile stimulus were obtained for two groups of subjects. Group 1 adjusted the vibrotactile stimulus to match the auditory stimulus, and Group 2 adjusted the auditory stimulus to match the vibrotactile stimulus. Stimulus-pulse durations and interstimulus intervals were varied over six experimental conditions for both groups. The variations in stimulus-pulse durations and interstimulus intervals had no appreciable effect on mean matching-function exponents for the two groups. A possible regression effect consistent with data from other psychophysical scaling studies was noted for matching functions of the two stimuli.     

Exploring the additive effects of stimulus quality and word frequency: The influence of local and list-wide prime relatedness

Stimulus quality and word frequency produce additive effects in lexical decision performance, whereas the semantic priming effect interacts with both stimulus quality and word frequency effects. This pattern places important constraints on models of visual word recognition. In Experiment 1, all three variables were investigated within a single speeded pronunciation study. The results indicated that the joint effects of stimulus quality and word frequency were dependent upon prime relatedness. In particular, an additive effect of stimulus quality and word frequency was found after related primes, and an interactive effect was found after unrelated primes. It was hypothesized that this pattern reflects an adaptive reliance on related prime information within the experimental context. In Experiment 2, related primes were eliminated from the list, and the interactive effects of stimulus quality and word frequency found following unrelated primes in Experiment 1 reverted to additive effects for the same unrelated prime conditions. The results are supportive of a flexible lexical processor that adapts to both local prime information and global list-wide context.     

Interlateral asymmetry in the time course of the effect of a peripheral prime stimulus

Evidence exists that both right and left hemisphere attentional mechanisms are mobilized when attention is directed to the right visual hemifield and only right hemisphere attentional mechanisms are mobilized when attention is directed to the left visual hemifield. This arrangement might lead to a rightward bias of automatic attention. The hypothesis was investigated by testing male volunteers, wherein a "location discrimination" reaction time task (Experiments 1 and 3) and a "location and shape discrimination" reaction time task (Experiments 2 and 4) were used. Unilateral (Experiments 1 and 2) and unilateral or bilateral (Experiments 3 and 4) peripheral visual prime stimuli were used to control attention. Reaction time to a small visual target stimulus in the same location or in the horizontally opposite location was evaluated. Stimulus onset asynchronies (SOAs) were 34, 50, 67, 83 and 100 ms. An important prime stimulus attentional effect was observed as early as 50 ms in the four experiments. In Experiments 2, 3 and 4, this effect was larger when the prime stimulus occurred in the right hemifield than when it occurred in the left hemifield for SOA 100 ms. In Experiment 4, when the prime stimulus occurred simultaneously in both hemifields, reaction time was faster for the right hemifield and for SOA 100 ms. These results indicate that automatic attention tends to favor the right side of space, particularly when identification of the target stimulus shape is required.     

Perceptual size discrimination requires awareness and late visual areas: A continuous flash suppression and interocular transfer study

We applied continuous flash suppression (CFS) during an interocular transfer paradigm to evaluate the importance of awareness and the contribution of early versus late visual structures in size recognition. Specifically, we tested if size judgements of a visible target could be influenced by a congruent or incongruent prime presented to the same or different eye. Without CFS, participants categorised a target as “small” or “large” more quickly when it was preceded by a congruent prime – regardless of whether the prime and target were presented to the same or different eye. Interocular transfer enabled us to infer that the observed priming was mediated by late visual areas. In contrast, there was no priming under CFS, which underscores the importance of awareness. We conclude that awareness and late visual structures are important for size perception and that any subconscious processing of the stimulus has minimal effect on size recognition.     

The interaction between response effects during the acquisition of response priming

In three experiments we investigated the role of associative learning in the acquisition of response priming by effect stimuli, by examining their interaction during response-effect learning. Having replicated the ability of visual effect stimuli to prime their associated responses, we paired a response with a compound consisting of visual and auditory effects before assessing the ability of the auditory effect stimulus to prime the response. This priming was reduced if the visual stimulus had been pre-trained as an effect of the response. By contrast, priming by the visual effect stimulus was potentiated when the auditory effect had been pre-trained. We interpret these interactions in terms of contemporary associative learning theory derived from studies of conditioning.     

Intermittency of visual information and the frequency of rhythmical force production

The authors examined the influence of intermittent (40-5,000 ms) visual information on the control of rhythmical isometric force output (0.5, 2.0, and 4.0 Hz) in 10 participants. Force variability decreased as a function of less intermittent visual information only in the 0.5- and 2.0-Hz tasks. Vision influenced the frequency structure of force output through 0-12 Hz in the 0.5-Hz task, but in only the 10.0- to 12.0-Hz range in the 2.0-Hz task and not in the 4.0-Hz task. The effective use of intermittent visual information in force output was mediated by task frequency, and that mediation was reflected in the differential emphasis of feedback and feedforward processes over multiple timescales of control.     

Apparent haptic movement

When as were presented with 150-Hz vibrotactile bursts at two loci on the skin of the thigh and permitted to adjust the time between burst onsets, they reported good apparent movement between the loci. The time between stimulus onsets for optimal movement was found to vary directly with the duration of the stimulus. Replication of the experiment with electrocutaneous stimuli at 1 KHz yielded similar results. Comparison of the data with results from a study of visual apparent movement revealed no difference between the two modalities for the relationship between stimulus onset intervals and stimulus duration. The significance of the results for hypotheses about the processes underlying perception of apparent movement is discussed.     

Affective priming of emotional pictures in parafoveal vision: Left visual field advantage

This study investigated whether stimulus affective content can be extracted from visual scenes when these appear in parafoveal locations of the visual field and are foveally masked, and whether there is lateralization involved. Parafoveal prime pleasant or unpleasant scenes were presented for 150 msec 2.5° away from fixation and were followed by a foveal probe scene that was either congruent or incongruent in emotional valence with the prime. Participants responded whether the probe was emotionally positive or negative. Affective priming was demonstrated by shorter response latencies for congruent than for incongruent prime-probe pairs. This effect occurred when the prime was presented in the left visual field at a 300-msec prime-probe stimulus onset asynchrony, even when the prime and the probe were different in physical appearance and semantic category. This result reveals that the affective significance of emotional stimuli can be assessed early through covert attention mechanisms, in the absence of overt eye fixations on the stimuli, and suggests that right-hemisphere dominance is involved.     

Probing Representations of Gymnastics Movements: A Visual Priming Study

In this study, we designed a visual short‐term priming paradigm to investigate the mechanisms underlying the priming of movements and to probe movement representations in motor experts and matched controls. We employed static visual stimuli that implied or not human whole‐body movements, that is, gymnastics movements and static positions. Twelve elite female gymnasts and twelve matched controls performed a speeded two‐choice response time task. The participants were presented with congruent and incongruent prime‐target pairs and had to decide whether the target stimulus represented a gymnastics movement or a static position. First, a visual priming effect was observed in the two groups. Second, a stimulus–response rote association could not easily account for our results. Novel primes never presented as targets could also prime the targets. Third, by manipulating three levels of prime‐target relations in moving congruent pairs, we demonstrated that the more similar prime‐target pairs, the greater the facilitation in target. Lastly, gymnastics motor expertise impacted on priming effects.     

Orientation invariance in visual object priming depends on prime—target asynchrony

Two experiments are reported in which orientation effects on visual object recognition latency were examined. In Experiment 1, we assessed picture-naming performance as a function of image-plane stimulus orientation and found increasing response times with increased misorientation of the stimulus. In Experiment 2, we examined the repetition priming effect on the identification of upright targets as a function of prime orientation. With time delays of 100, 200, or 500 msec between the onset of the prime and that of the target (i.e., stimulus onset asynchrony [SOA]), the magnitude of the priming effect decreased with increasing misorientation of the prime. These results contrast with the orientationinvariant priming effects reported in some previous repetition priming studies. These investigations all used relatively long prime—target SOAs. Confirming the crucial role of the latter variable, Experiment 2 shows that the magnitude of the repetition priming effect is invariant across prime orientations with an SOA of 1,000 msec. The possible implications of the present observations with respect to the issue of orientation invariance versus dependency of the visual object recognition process are discussed.     

Distractor clustering enhances detection speed and accuracy during selective listening

The effects of distractor clustering on target detection were examined in two experiments in which subjects attended to binaural tone bursts of one frequency while ignoring distracting tones of two competing frequencies. The subjects pressed a button in response to occasional target tones of longer duration (Experiment 1) or increased loudness (Experiment 2). In evenly spaced conditions, attended and distractor frequencies differed by 6 and 12 semitones, respectively (e.g., 2096-Hz targets vs. 1482- and 1048-Hz distractors). In clustered conditions, distractor frequencies were grouped; attended tones differed from the distractors by 6 and 7 semitones, respectively (e.g., 2096-Hz targets vs. 1482- and 1400-Hz distractors). The tones were presented in randomized sequences at fixed or random stimulus onset asynchronies (SOAs). In both experiments, clustering of the unattended frequencies improved the detectability of targets and speeded target reaction times, Similar effects were found at fixed and variable SO As. Results from the analysis of stimulus sequence suggest that clustering improved performance primarily by reducing the interference caused by distractors that immediately preceded the target.     

Response activation in overlapping tasks and the response-selection bottleneck

The authors investigated the impact of response activation on dual-task performance by presenting a subliminal prime before the stimulus in Task 2 (S2) of a psychological refractory period (PRP) task. Congruence between prime and S2 modulated the reaction times in Task 2 at short stimulus onset asynchrony despite a PRP effect. This Task 2 congruence effect was paralleled by a Task 1 congruence effect and emerged exclusively under conditions of cross talk, whereas it did not occur under dual-task conditions preventing cross talk between tasks. This suggests that response activation operates during the PRP in dual tasks and affects the response times in Task 2 via cross talk between common processing elements at prebottleneck stages but not by directly affecting the postbottleneck stages.     

Orientation invariance in visual object priming depends on prime-target asynchrony

Two experiments are reported in which orientation effects on visual object recognition latency were examined. In Experiment 1, we assessed picture-naming performance as a function of image-plane stimulus orientation and found increasing response times with increased misorientation of the stimulus. In Experiment 2, we examined the repetition priming effect on the identification of upright targets as a function of prime orientation. With time delays of 100, 200, or 500 msec between the onset of the prime and that of the target (i.e., stimulus onset asynchrony [SOA]), the magnitude of the priming effect decreased with increasing misorientation of the prime. These results contrast with the orientation-invariant priming effects reported in some previous repetition priming studies. These investigations all used relatively long prime-target SOAs. Confirming the crucial role of the latter variable, Experiment 2 shows that the magnitude of the repetition priming effect is invariant across prime orientations with an SOA of 1,000 msec. The possible implications of the present observations with respect to the issue of orientation invariance versus dependency of the visual object recognition processare discussed.     

The effect of an after-coming random pattern on the perception of brief visual stimuli

The perception of briefly exposed visual forms is shown to be masked by an after- coming random pattern stimulus of approximately equal intensity. This effect occurs only under certain well defined conditions; it is limited by the minimum stimulus exposure time in excess of threshold which overcomes masking (critical stimulus duration) as well as by the minimum interval between presentation of the two stimuli which permits evasion of the masking action (critical interval). Over the range of stimulus duration in which masking occurs, critical interval varied with stimulus duration in such a way that the interval multiplied by the stimulus duration equals a constant. Critical stimulus duration and critical interval at threshold are shown to vary little under a variety of conditions. The effect of the random pattern stimulus is limited to the part of the visual field to which it is presented.