A new effect of luminance gradient on achromatic simultaneous contrast

A new effect in the domain of achromatic simultaneous contrast has been observed. A middle gray region placed at the center of an area filled by a linear achromatic gradient from black (outer part) to white (inner part) is perceived as being much darker than an identical middle gray region surrounded by a reversed gradient. By using a matching task in two experiments, it has been shown that this phenomenon is much stronger than the classical achromatic simultaneous contrast effect. The new effect is interpreted in terms of thealbedo hypothesis.     

The simultaneous acquisition effect: simultaneous task learning inhibits memory for order

Delayed recall of a list of words learned simultaneously with other lists is superior to that of a list of words learned singly. A Brown-Peterson-like task was used to investigate this simultaneous acquisition effect from the perspective of the item-order distinction. It was hypothesized that simultaneous task learning would impede the encoding of order information but promote the encoding of item-specific information relative to single-task learning. The results of the first four experiments strongly supported the hypothesis that simultaneous task learning decreases the encoding of order information but provided no evidence that it facilitated the encoding of item-specific information. Additionally, Experiment 5 showed that the simultaneous acquisition effect did not occur in a mixed-list design, demonstrating an important boundary condition of the effect.     

Monitoring simultaneous auditory messages

If a S is asked to monitor two simultaneous auditory speech messages and to report only on the occurrence of target words appearing at random in either message, then it is shown that he witt fail to detect all of them but will detect significantly more than half. The targets used in these experiments were immediate repeats of text words. The results reject theories that part of the sensory input is blocked or that all is recognized. Detection performance was a function of rate of speech and of intertarget interval; there was a small, not significant, effect of instruction to recognize message content.     

A new method for solving simultaneous linear equations associated with multivariate analysis

A method is outlined whereby the equations resulting from multivariate analyses may be solved. Only the upper or lower triangular coefficient matrix need be employed. All solutions involving any combination(s) of the variables represented in the coefficient matrix are readily obtainable without permutation of the matrix. All solutions are given immediately without the need for back solving. One variable is added to or subtracted from the regression equation with each application of the method. The method may be applied as repeatedly as needed for any particular solution.     

Color-selectivity in simultaneous motion contrast

Thirty-two Ss were required to estimate the apparent motion of stationary vertical lines viewed against a background of moving vertical lines when both patterns were seen by the same eye (monoptic conditions) or the center pattern was seen by one eye and the surrounds by the other eye (dichoptic conditions). The stationary lines appeared to be moving from right to left as the surrounds moved left to right. The simultaneous motion contrast found under monoptic conditions was maximal when the center pattern and the surrounds were the same color and was reduced when they differed in color. The surrounds had limited influence on the apparent motion of the center section under dichoptic condition, and the color relationship was no longer important. Related color selectivity has been reported for the motion aftereffect (successive motion contrast), and both sets of data can be attributed to inlaibitory interaction (simultaneous in one case and successive in the other) among neural detectors tuned to wavelength as well as the direction of image motion.     

Stimulus function in simultaneous discrimination

In discrimination learning, the negativity of the stimulus correlated with nonreinforcement (S-) declines after 100 training trials while the stimulus correlated with reinforcement (S+) is paradoxically more positive with lesser amounts of discrimination training. Training subjects on two simultaneous discrimination tasks revealed a within-subjects overlearning reversal effect, where a more-frequently presented discrimination problem was better learned in reversal than was a discrimination problem presented less frequently during training.     

Cerebral lateralization in simultaneous interpretation

Cerebral asymmetries for L1 (Italian), L2 (English), and L3 (French, German, Spanish, or Russian) were studied, by using a verbal-manual interference paradigm, in a group of Italian right-handed polyglot female students at the Scuola Superiore di Lingue Moderne per Interpreti e Traduttori (SSLM-School for Interpreters and Translators) of the University of Trieste and in a control group of right-handed monolingual female students at the Medical School of the University of Trieste. In an automatic speech production task no significant cerebral lateralization was found for the mother tongue (L1) either in the interpreting students or in the control group; the interpreting students were not significantly lateralized for the third language (L3), while weak left hemispheric lateralization was shown for L2. A significantly higher degree of verbal-manual interference was found for L1 than for L2 and L3. A significantly higher disruption rate occurred in the meaning-based mode of simultaneous interpretation (from L2 into L1 and vice versa) than in the word-for-word mode (from L2 into L1 and vice versa). No significant overall or hemispheric differences were found during simultaneous interpretation from L1 into L2 or from L2 into L1.     

Does preoccupation impair hazard perception? A simultaneous EEG and Eye Tracking study

The aim of this current study was to test the hypothesis that contemplating a recent mobile telephone conversation has a detrimental effect on measures of attentional processing in a driving situation. In this within-subjects design, hazard perception performance was compared between high and no cognitive load conditions (with or without a puzzle to solve). We tested 17 participants, all of whom were required to be in possession of a DVLA approved driving license and had completed the hazard perception portion of the British driving test. A novel dual-task paradigm, which did not require subjects to process or produce verbal information during the primary task, was employed to increase participants’ cognitive load. Participants were assessed on three categories of performance measures: behavioural, eye movements and cortical activity between both high and no cognitive load conditions whilst watching 20 clips from a hazard perception test. This study was run in a laboratory of the Psychology Research Wing at the University of Dundee. Behavioural findings from the hazard perception test indicate significantly increased reaction times to hazardous stimuli and significantly increased false alarm rates to non-hazardous stimuli in the high cognitive load condition (when contemplating a previous conversation). Analyses of eye movements indicated significant increases in blink frequencies, higher saccade peak velocities and a significant reduction in the spread of fixations along the horizontal axis. Results from EEG recordings showed a significant increase in frontal and a significant decrease in occipital theta activity within the high load condition. Findings were interpreted within the framework of Corbetta, Patel and Schulmann’s (2008) networks model of attention control. Our findings suggest that preoccupation with a recent conversation negatively influences the modulatory effect of the central executive on both the stimulus as well as goal-driven networks of the brain.     

A new device to present textured stimuli to touch with simultaneous EEG recording

The study of touch has recently grown, due mainly to the extensive use of several types of actuators that stimulate several subsystems of touch. There is a widespread interest in applying these mechanisms to the study of the neurophysiological correlates of tactual perception. In this article, we present a new device (the tactile spinning wheel [TSW]) for delivering textured surfaces to the finger pad. The TSW allows one to control several parameters of the stimulation (angular speed, texture, etc.) and, connected to an EEG recording system, makes it possible to study neural electrophysiological events. The device consists of a rotating platform on which the tactile stimuli are fixed, a system that synchronizes stimuli onset with the EEG system, and an electronic interface that controls the platform. We present the technical details of the TSW, its calibration, and some experimental results we have obtained with this device.     

Instructive feedback: A comparison of simultaneous and alternating presentation of non-target stimuli

Instructive feedback involves presenting extra, non-target stimuli in the consequent events for children's responses. Two methods of presenting instructive feedback during direct instruction were compared. These methods involved presenting two extra stimuli on all trials, and presenting the two extra stimuli separately on alternating trials. Preschool students were taught coin combinations using a constant time delay procedure with instructive feedback stimuli added to both praise and correction statements. An adapted alternating treatments design was used to evaluate the two methods of presenting instructive feedback. The students were assessed to determine the extent to which instructive feedback stimuli were learned. The results indicate that students learned some of the instructive feedback stimuli and no consistent differences in the effectiveness of the two presentation methods were noted. Further, relationships between the two instructive feedback stimuli appeared to be established. Implications for instruction and future research are discussed.     

Peak shift following simultaneous discriminations

Pigeons were exposed to stimuli presented on two keys. For some birds, the stimuli varied in a dimension of visual flicker-rate, and for others they varied in visual intensity. During differential training, concurrent schedules operated, with one stimulus correlated with one schedule and another stimulus correlated with a second schedule that arranged a lower, or zero, rate of reinforcement. The stimuli were alternated randomly on the two keys. Generalization tests were given in which the original two, and seven other stimuli lying in the same dimension, were presented in pairs on the two keys in various combinations. In the generalization test given after differential training, each bird showed peak shift. The data did not support explanation for peak shift that gave critical emphasis to whether stimuli were presented simultaneously or successively during differential training.     

Change deafness for simultaneous voices

Apparent changes in auditory scenes are often unnoticed. This change deafness phenomenon was examined in auditory scenes that comprise human voices. In two experiments, listeners were required to detect changes between two auditory scenes comprising two, three, and four talkers who voiced four‐syllable words. One of the voices in the first scene was randomly selected and was replaced with a new word in change trials. The rationale was that higher stimulus familiarity conferred by human voices compared to other everyday sounds, together with encoding and memory advantages for verbal stimuli and the modular processing of speech in auditory processing, should positively influence the change detection efficiency, and the change deafness phenomenon should not be observed when listeners are explicitly required to detect the obvious changes. Contrary to the prediction, change deafness was significantly observed in three‐ and four‐talker conditions. This indicates that change deafness occurs in listeners even for highly familiar stimuli. This suggests the limited ability for perceptual organization of auditory scenes comprising even a relatively small number of voices (three or four).