Infant perception of audio-visual speech synchrony.

Three experiments investigated perception of audio-visual (A-V) speech synchrony in 4- to 10-month-old infants. Experiments 1 and 2 used a convergent-operations approach by habituating infants to an audiovisually synchronous syllable (Experiment 1) and then testing for detection of increasing degrees of A-V asynchrony (366, 500, and 666 ms) or by habituating infants to a detectably asynchronous syllable (666 ms; Experiment 2) and then testing for detection of decreasing degrees of asynchrony (500, 366, and 0 ms). Following habituation to the synchronous syllable, infants detected only the largest A-V asynchrony (0 ms vs. 666 ms), whereas following habituation to the asynchronous syllable, infants detected the largest asynchrony (666 ms vs. 0 ms) as well as a smaller one (666 ms vs. 366 ms). Experiment 3 investigated the underlying mechanism of A-V asynchrony detection and indicated that responsiveness was based on a sensitivity to stimulus-energy onsets rather than the dynamic correlation between acoustic and visible utterance attributes. These findings demonstrated that infant perception of A-V speech synchrony is subject to the effects of short-term experience and that it is driven by a low-level, domain-general mechanism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The one that does, leads: Action relations influence the perceived temporal order of graspable objects.

Perception and action are influenced by the “possibilities for action” in the environment. Neuropsychological studies (e.g., Riddoch, Humphreys, Edwards, Baker, & Willson, 2003) have demonstrated that objects that are perceived to be interacting (e.g., a corkscrew going toward the top of a wine bottle) are perceptually integrated into a functional unit, facilitating report of both objects. In addition, patients with parietal damage tend to report the “active” item of the pair (the corkscrew in the above example) when the objects are positioned for action, overriding their spatial bias toward the ipsilesional side. Using a temporal order judgment task we show for the first time that normal viewers judge that active objects appear earlier when they are positioned correctly for action. This effect is not dependent on a learned relationship between objects, or on the active object being integrated at a perceptual level with the object it is paired with. The data suggest that actions afforded by a correctly positioned active object permeate normal perceptual judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intertrial interval as a contextual stimulus: Further analysis of a novel asymmetry in temporal discrimination learning.

Four experiments investigated discrimination learning when the duration of the intertrial interval (ITI) signaled whether or not the next conditional stimulus (CS) would be paired with food pellets. Rats received presentations of a 10-s CS separated half the time by long ITIs and half the time by short ITIs. When the long ITI signaled that the CS would be reinforced and the short interval signaled that it would not be (Long+/Short?), rats learned the discrimination readily. However, when the short ITI signaled that the CS would be reinforced and the long interval signaled that it would not (Short+/Long?), discrimination learning was much slower. Experiment 1 compared Long+/Short? and Short+/Long? discrimination learning with 16-min/4-min or 4-min/1-min ITI combinations. Experiment 2 found no evidence that Short+/Long? learning is inferior because the temporal cue corresponding to the short interval is ambiguous. Experiment 3 found no evidence that Short+/Long? learning is poor because the end of a long ITI signals a substantial reduction in delay to the next reinforcer. Long+/Short? learning may be faster than Short+/Long?because elapsing time involves exposure to a sequence of hypothetical stimulus elements (e.g., A then B), and feature-positive discriminations (AB+/A?) are learned quicker than feature-negative discriminations (A+/AB?). Consistent with this view, Experiment 4 found a robust feature-positive effect when sequentially presented CSs played the role of elements A and B. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of methamphetanine on duration discrimination.

Experiments 1 and 2 address the controversy regarding the reliability of methamphetamine effects on interval timing. A temporal discrimination procedure was used, in which the rats were reinforced for pressing the left or the right levers after short and long signals, respectively. Methamphetamine (0.5 mg/kg sc) severely disrupted operant performance at 20-100 min after injection, which disabled the measurement of drug effects on temporal perception (Experiment 1). The same dose of methamphetamine shifted the psychometric function to the left at 100-180 min after injection, indicating an increase in subjective durations (Experiment 2). Although these results confirm the role of dopamine in interval timing, that a change in the speed of a neural clock mediates the methamphetamine-induced change in temporal perception is still a working hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning and discrimination of audiovisual events in human infants: The hierarchical relation between intersensory temporal synchrony and rhythmic pattern cues.

This study examined 4- to 10-month-old infants' perception of audio-visual (A-V) temporal synchrony cues in the presence or absence of rhythmic pattern cues. Experiment 1 established that infants of all ages could successfully discriminate between two different audiovisual rhythmic events. Experiment 2 showed that only 10-month-old infants detected a desynchronization of the auditory and visual components of a rhythmical event. Experiment 3 showed that 4- to 8-month-old infants could detect A-V desynchronization but only when the audiovisual event was nonrhythmic. These results show that initially in development infants attend to the overall temporal structure of rhythmic audiovisual events but that later in development they become capable of perceiving the embedded intersensory temporal synchrony relations as well. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of weight intensity on discrimination thresholds of normals and schizophrenics.

20 male chronic schizophrenics, 12 chronic disturbed schizophrenics, and 20 normal controls were tested for upper difference limens from both a 40-gm (light) and 400-gm (heavy) standard weight. Weight discrimination thresholds were found to be significantly elevated as a function of severity of pathology in the schizophrenic groups and also at the lighter weight intensity. Both groups of schizophrenics showed significantly greater improvement than normals with the heavy weights. The less disturbed chronic schizophrenics were not significantly different from normals at the heavy intensity. The results support the hypothesis of a schizophrenic deficit in proprioceptive acuity and suggest that this deficit is the result of insufficient proprioceptive feedback. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Overloading Temporal Memory.

This study tested the hypothesis that memory is a major source of variance in temporal processing. Participants categorized intervals as short or long. The number of base durations and interval types mixed within blocks of trials varied from 1 session to another. Results revealed that mixing 2 base durations within blocks increased categorization errors, but mixing 2 marker types did not. Results are attributed to the involvement of more than 1 memory representation, which is argued to show the critical role of memory in temporal processing. Because mixing modalities has no such effect, it was argued that modalities share a common representation in memory. Finally, there was no difference in the perceived duration of auditory and visually marked intervals, which is inconsistent with most reports on this effect. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The influence of an affective set on disyllable recognition thresholds.

"The present experiment was designed to test the hypothesis that there is a relationship between motivational factors and perception. Electric shock was employed to induce anxiety provoking conditions in relation to the perception of certain verbal symbols, and changes in their speed of perception were noted." The words were associated with a conditioned response and conditioning was more rapid with shock than nonshock syllables. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus dynamics and temporal discrimination: Implications for pacemakers.

The purpose of the present study was to observe the functional relationship between stimulus dynamics and stimulus duration judgments in humans. Stimulus duration was defined as the length of time that a spinning sphere appeared on a computer screen. Stimulus dynamics were defined by how quickly the sphere rotated on its y-axis. Using a logarithmic scale, a psychophysical bisection task was used to divide stimulus durations into two categories, short and long. Across three experiments, participants’ duration judgments were longer the faster the sphere was rotated. This effect was observed over both a long and short temporal scale and over a wide range of stimulus dynamics despite the fact that the reinforcement contingencies penalized participants for this effect. The results are discussed in terms of perceived change as the possible basis of temporal duration estimation. This hypothesis was investigated through applications of the leading quantitative models of temporal discrimination to the present data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Smoking Urge on Temporal Cognition.

The authors examined temporal aspects of smoking urge. In Experiment 1, smokers assigned to high- or low-urge conditions were informed they would be allowed to smoke in 2.5 min. They next completed measures of time perception. High-urge smokers reported 45 s to pass significantly more slowly than did low-urge smokers. In Experiment 2, the high-urge smokers from Experiment 1 anticipated that their urges would climb steadily over the next 45 min if they were not permitted to smoke. Another group of high-urge smokers actually reported their urges over 45 min. These urge ratings did not show the steady rise anticipated by the first group. Results suggest that smoking urge may affect time perception and that craving smokers overpredict the duration and intensity of their own future smoking urges if they abstain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Conditions for Temporal Tracking Under Interval Schedules of Reinforcement.

On many cyclic-interval schedules, animals adjust their postreinforcement pause to follow the interval duration (temporal tracking). Six pigeons were trained on a series of square-wave (2-valued) interval schedules (e.g., 12 fixed-interval [FI] 60, 4 FI 180). Experiment 1 showed that pigeons track square-wave schedules, except those with a single long interval per cycle. Experiments 2 and 3 established that tracking and nontracking are learned and both can transfer from one cyclic schedule to another. Experiment 4 demonstrated that pigeons track a schedule with a single short interval per cycle, suggesting that a dual process--cuing and tracking--is necessary to explain behavior on these schedules. These findings suggest a potential explanation for earlier results that reported a failure to track square-wave schedules. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The discrimination of temporal fine structure in call-like harmonic sounds by birds.

Thresholds for discriminating changes in the temporal fine structure of call-like, harmonic sounds were measured in zebra finches (Taeniopygia guttata) and budgerigars (Melopsittacus undulatus). Birds could detect changes in periods as short as 1.225 ms at near 100% accuracy even when spectral and envelope cues were identical, as in time-reversed stimuli. Humans performed poorly on such stimuli, paralleling results from previous studies. Bird thresholds were in the range of those reported in neurophysiological studies of the songbird high vocal center (HVC) to temporally modified conspecific songs. Taken together, these results show that birds can hear differences in temporal fine structure in their natural vocalizations that go beyond human capabilities, but whether these abilities have communicative relevance remains to be seen. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of Emotion on Memory for Temporal Information.

Contextual information, such as color and spatial location, has been found to be better remembered for emotional than for neutral items. The current study examined whether the influence of emotion extends to memory for another fundamental feature of episodic memory: temporal information. Results from a list-discrimination paradigm showed that (a) item memory was enhanced for both negative and positive pictures compared with neutral ones and was better for negative than for positive pictures and (b) temporal information was better remembered for negative than for positive and neutral pictures, whereas positive and neutral pictures did not differ from each other. These findings are discussed in relation to the processes involved in memory for temporal information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhythmic Masking Release: Effects of Asynchrony, Temporal Overlap, Harmonic Relations, and Source Separation on Cross-Spectral Grouping.

The rhythm created by spacing a series of brief tones in a regular pattern can be disguised by interleaving identical distractors at irregular intervals. The disguised rhythm can be unmasked if the distractors are allocated to a separate stream from the rhythm by integration with temporally overlapping captors. Listeners identified which of 2 rhythms was presented, and the accuracy and rated clarity of their judgment was used to estimate the fusion of the distractors and captors. The extent of fusion depended primarily on onset asynchrony and degree of temporal overlap. Harmonic relations had some influence, but only an extreme difference in spatial location was effective (dichotic presentation). Both preattentive and attentionally driven processes governed performance. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The effects of aging on memory for sequentially presented objects in rats.

The current study investigated memory for sequentially presented objects in young rats 6 months old (n = 12) and aged rats 24 months old (n = 12). Rats were tested on a task involving three exploratory trials and one probe test. During the exploratory trials, the rat explored a set of three sequentially presented object pairs (A-A, B-B, and C-C) for 5 min per pair with a 3-min delay between each pair. Following the exploratory trials, a probe test was conducted where the rat was presented simultaneously with one object from the first exploratory trial (A) and one object from the third exploratory trial (C). Results from the exploratory trials showed no significant age-related differences in exploration, indicating that 24-month-old rats explored the object pairs as much as 6-month-old rats. The probe test demonstrated that 6-month-old rats spent significantly more time exploring object A compared to object C, indicating that young rats show intact temporal order memory for the exploratory trial objects. However, 24-month-old rats showed no preference for object A and spent a relatively equal amount of time exploring objects A and C. The results suggest that temporal order memory declines as a result of age-related changes in the rodent brain. The findings also may reflect differences in attraction to objects with different memory strengths. Since age-related differences were not detected during the exploratory trials, age-related differences on the probe trial were not due solely to decreased exploration, motivation, or locomotion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal Construal Effects on Abstract and Concrete Thinking: Consequences for Insight and Creative Cognition.

Six studies investigate whether and how distant future time perspective facilitates abstract thinking and impedes concrete thinking by altering the level at which mental representations are construed. In Experiments 1-3, participants who envisioned their lives and imagined themselves engaging in a task 1 year later as opposed to the next day subsequently performed better on a series of insight tasks. In Experiments 4 and 5 a distal perspective was found to improve creative generation of abstract solutions. Moreover, Experiment 5 demonstrated a similar effect with temporal distance manipulated indirectly, by making participants imagine their lives in general a year from now versus tomorrow prior to performance. In Experiment 6, distant time perspective undermined rather than enhanced analytical problem solving. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Moderating effects of three coping strategies and self-esteem on perceived discrimination and depressive symptoms: A minority stress model for Asian international students.

This study examined 3 coping strategies (reflective, suppressive, and reactive), along with self-esteem, as moderators of the relation between perceived discrimination and depressive symptoms. International students (N = 354) from China, India, Korea, Taiwan, and Hong Kong provided data via an online survey. The role of perceived general stress was statistically controlled. Hierarchical regression analyses indicated a significant direct effect of perceived discrimination, a significant 2-way interaction of perceived discrimination and suppressive coping, and a significant 3-way interaction of perceived discrimination, reactive coping, and self-esteem in predicting depressive symptoms. An increased tendency to use suppressive coping appeared to strengthen the association between perceived discrimination and depressive symptoms. In contrast, the association between perceived discrimination and depressive symptoms was not significant when reactive coping was infrequently used, but only for students with relatively high self-esteem. (PsycINFO Database Record (c) 2010 APA, all rights reserved)