Time course of visual attention with emotional faces

When a briefly presented and then masked visual object is identified, it impairs the identification of the second target for several hundred milliseconds. This phenomenon is known as attentional blink or attentional dwell time. The present study is an attempt to investigate the role of salient emotional information in shifts of covert visual attention over time. Two experiments were conducted using the dwell time paradigm, in which two successive targets are presented at different locations with a variable stimulus onset asynchrony (SOA). In the first experiment, real emotional faces (happy/sad) were presented as the first target, and letters (L/T) were presented as the second target. The order of stimulus presentation was reversed in the second experiment. In the first experiment, identification of the letters preceded by happy faces showed better performance than did those preceded by sad faces at SOAs less than 200 msec. Similarly, happy faces were identified better than sad faces were at short SOAs in Experiment 2. The results show that the time course of visual attention is dependent on emotional content of the stimuli. The findings indicate that happy faces are associated with distributed attention or broad scope of attention and require fewer attentional resources than do sad faces.     

Salience-based progression of visual attention: Time course

In a visual search task, visual attention progresses from the most to the least salient item until a target is found. The time course of such salience-based progression remains unclear although the temporal deployment seems as crucial as the spatial deployment. The present study investigated how the general hierarchical pattern takes place. Healthy volunteers were presented with a primed visual search paradigm in which the primes consisted of three items differing in salience for either 33, 50 or 100 ms. Subsequently one of them became the target and participants had to make a judgment about it. In order to progress on the basis of salience, attention seemed first to be captured by the most salient item. Secondly, the first two most salient items seemed both encompassed within the attentional spotlight. At that time, the least salient item seemed inhibited, completing the stepwise progression of attention. In summary, our data suggest that the hierarchical pattern is built up over time through orienting and expansion of the spotlight, and inhibition of the least salient signals. Furthermore, complementary analyses revealed a proximity effect influencing the selection of the next location to visit. As predicted by different computational models, items located closely to the first visited location were more prone to attract attention than distant items but interestingly enough, this effect only applied to the least salient item suggesting a balance between salience and proximity criteria. Critically also, salience and proximity effects seem to have different time courses. Results are only partially explained by current visual attention models and require further investigation.     

Time course of visual attention across perceptual levels and objects

Theories of shifts of visual attention based on attentional blink or dwell time do not directly address shifts of attention across different levels (global or local) involving multiple objects. Two experiments were conducted employing the attentional dwell time paradigm to investigate the shifts of visual attention between objects selected at same or different levels. Participants were instructed to identify two successive compound stimuli at a pre-specified level (global or local) presented at two different locations with variable SOA. The initial pair of locations in which the stimulus was presented was fixed in Experiment 1 but not in Experiment 2. Experiment 1 results showed very little impairment for second target identification when both the targets were at the global level. Attentional shift was better with both targets at the same level compared to different levels. Experiment 2 results showed that local followed by global target identification is difficult at short SOAs compared to other conditions. The results indicate that scope of attention affects the time course of visual attention. Global processing could be performed with very little capacity limitation simultaneously with distributed attention. The default mode of attention might be distributed and attention becomes focused for target identification. Different mechanisms may underlie shifts in focused attention between different locations and changes in attentional set required by changes in perceptual levels.     

Hearing what the eyes see: auditory encoding of visual temporal sequences

When the senses deliver conflicting information, vision dominates spatial processing, and audition dominates temporal processing. We asked whether this sensory specialization results in cross-modal encoding of unisensory input into the task-appropriate modality. Specifically, we investigated whether visually portrayed temporal structure receives automatic, obligatory encoding in the auditory domain. In three experiments, observers judged whether the changes in two successive visual sequences followed the same or different rhythms. We assessed temporal representations by measuring the extent to which both task-irrelevant auditory information and task-irrelevant visual information interfered with rhythm discrimination. Incongruent auditory information significantly disrupted task performance, particularly when presented during encoding; by contrast, varying the nature of the rhythm-depicting visual changes had minimal impact on performance. Evidently, the perceptual system automatically and obligatorily abstracts temporal structure from its visual form and represents this structure using an auditory code, resulting in the experience of "hearing visual rhythms."     

Time course of visual information utilization during fixations in reading

College students read short texts from a cathode-ray tube as their eye movements were being monitored. During selected fixations, the text was briefly masked and then it reappeared with one word changed. Subjects often were unaware that the word had changed. Sometimes they reported seeing the first presented word, sometimes the second presented word, and sometimes both. When only one word was reported, two factors were found to determine which one it was: the length of time a word was present during the fixation and the predictability of a word in its context. The results suggested that visual information is utilized for reading at a crucial period during the fixation and that this crucial period can occur at different times on different fixations. The pattern of responses suggested that the first letter of a word is not utilized before other letters and that letters are not scanned from left to right during a fixation.     

The temporal course of visual pattern encoding: Effects of pattern goodness

Subjects typically display superior reproduction of good (redundant, symmetrical) visual patterns compared with poor ones. This pattern goodness effect could conceivably involve encoding processes, short-term memory processes, or response processes. The present experiments explored the time course of wholistic encoding of Garner dot patterns as a function of tachistoscopic exposure time, delay of backward masking, and post-mask shadowing. Within the specific framework of additive factors theory, Experiment I showed: (a) equal rates of encoding for all patterns since comparable slopes were obtained for the recall X processing time functions; and (b) superior absolute recall for good patterns since different intercepts were obtained. Experiment II demonstrated that when degree of encoding was initially equalized for all patterns, the rate of extraction of further information remained constant over available processing time and was unaffected by pattern goodness, slopes and intercepts for good versus poor patterns then being equal. Experiment III confirmed that, given some fixed duration of available processing time, information is abstracted at the same rate for all pattern regardless of the ratio stimulus display time to delay of mask onset. Experiment IV indicated that maintenance rehearsal normally occurs in the present experimental situation, and that very good patterns are somewhat less disrupted by shadowing over a three-second interval. While STM is thus implicated in the pattern goodness effect it does not follow that STM constitutes a complete explanation of the intercept differences reported here. Empirical evidence of response bias toward production of good patterns, however, was not found. It was shown that very good patterns are highly familiar and nameable, and proposed that they do consequently have an early encoding advantage.     

视觉工作记忆的巩固加工：时程、模式及机制

在视觉工作记忆加工过程中, 对记忆项目的维持及操作需要将转瞬即逝的感觉输入转换为稳定的记忆表征, 这一加工过程被定义为视觉工作记忆巩固。鉴于巩固在视觉工作记忆中所起到的“门控”作用, 研究者们已经发展出多种研究范式对其可能涉及的运作机制进行探讨。然而, 在不同范式下所观察到的巩固时程存在较大差异, 其所遵循的巩固模式也尚不清晰。此外, 对于巩固所涉及的理论及神经机制亦存在不同的观点。通过对比不同范式的差异性及梳理各方的观点, 可以有效推动这些问题的解决。未来研究除了可以在多种范式下对巩固模式进行验证, 还可以探究注意在巩固中的作用, 以及项目熟悉性等因素会对巩固加工产生何种影响。     

Object-based auditory and visual attention

Theories of visual attention argue that attention operates on perceptual objects, and thus that interactions between object formation and selective attention determine how competing sources interfere with perception. In auditory perception, theories of attention are less mature and no comprehensive framework exists to explain how attention influences perceptual abilities. However, the same principles that govern visual perception can explain many seemingly disparate auditory phenomena. In particular, many recent studies of 'informational masking' can be explained by failures of either auditory object formation or auditory object selection. This similarity suggests that the same neural mechanisms control attention and influence perception across different sensory modalities.     

S-R correspondence effects of irrelevant visual affordance: Time course and specificity of response activation

It has been suggested that representations for action, elicited by an object's visual affordance, serve to potentiate motor components (such as a specific hand) to respond to the most afforded action. In three experiments, participants performed speeded left-right button press responses to an imperative target superimposed onto a prime image of an object suggesting a visual affordance oriented to left or right visual space. The time course of response activation was measured by varying the onset time between the prime and target. Long-lasting and gradually developing correspondence effects were found between the suggested affordance of the prime and the side of response, with little effect of response modality (hands uncrossed, hands crossed, or foot response). We conclude that visual affordances can evoke an abstract spatial response code, potentiating a wide variety of lateralized responses corresponding with the affordance.     

Multidimensional encoding of visual form

The encoding of stimulus dimensions of visual form in the human S was investigated under conditions of threshold exposure durations. Three stimulus dhnensions defined on a spatial grating were investigated: spatial line frequency, grating orientation, and orientation of a transverse break in the lines of grating. Results support the conclusion that, within the general category of visual form, different primary stimulus dimensions such as spatial frequency and orientation may be encoded simultaneously, whereas, when the two stimulus components for report are defined on the same dimension (orientation), overall performance is consistent with the predictions of a single channel model.     

Parallel scanning of auditory and visual information

Two experiments involving memory retrieval of auditorilv and visually presented materials were performed. In Experiment I, subjects were presented with memory sets of 1, 2, or 4 stimuli and then with a test item to be classified as belonging or not belonging to the memory set. In Condition 1, each memory stimulus was a single, auditorily presented letter. In Condition 2, each memory stimulus was a visually presented letter. In Conditions 3 and 4, each memory stimulus was a pair of letters, one presented visually and the other auditorily. Mean reaction time (RT) for the classification task increased as a function of number of memory stimuli at equal rates for all four conditions. This was interpreted as evidence for a parallel scanning process in Conditions 3 and 4 where the auditory item and visual item of each memory stimulus pair can be scanned simultaneously. Experiment II compared memory retrieval for a simultaneous condition in which auditory and visual memory items were presented as pairs with a sequential condition in which mixed auditory-visual memory sets were presented one item at a time. RTs were shorter for the simultaneous condition. This was interpreted as evidence that parallel scanning may depend upon memory input parameters.     

The fidelity of visual and auditory memory

Psychonomic Bulletin & Review - Recent studies show that recognition memory for pictures is consistently better than recognition memory for sounds. The purpose of this experiment was to compare...     

Effect of interval between auditory and preceding visual stimuli on auditory sensitivity

Auditory thresholds were determined by a modified method of limits, in introverts, ambiverts and extraverts, under three intensities of light. Five determinations were made: one before, one during and three (30 sec., c. 8 and 16 min.) after the light stimulation. An analysis of variance of the data showed significant results for the interval conditions, the personality type and the interaction of these parameters, under the weak light. Interval effects were also significant under medium and strong light. A weak light increased, and a strong light decreased, auditory sensitivity when threshold determinations began 30 sec., but not more than about 8 min., after the light stimulation, in introverts.