Spatial stimulus cue information supplying auditory saltation

Auditory saltation is a misperception of the spatial location of repetitive, transient stimuli. It arises when clicks at one location are followed in perfect temporal cadence by identical clicks at a second location. This report describes two psychophysical experiments designed to examine the sensitivity of auditory saltation to different stimulus cues for auditory spatial perception. Experiment 1 was a dichotic study in which six different six-click train stimuli were used to generate the saltation effect. Clicks lateralised by using interaural time differences and clicks lateralised by using interaural level differences produced equivalent saltation effects, confirming an earlier finding. Switching the stimulus cue from an interaural time difference to an interaural level difference (or the reverse) in mid train was inconsequential to the saltation illusion. Experiment 2 was a free-field study in which subjects rated the illusory motion generated by clicks emitted from two sound sources symmetrically disposed around the interaural axis, ie on the same cone of confusion in the auditory hemifield opposite one ear. Stimuli in such positions produce spatial location judgments that are based more heavily on monaural spectral information than on binaural computations. The free-field stimuli produced robust saltation. The data from both experiments are consistent with the view that auditory saltation can emerge from spatial processing, irrespective of the stimulus cue information used to determine click laterality or location.     

The effects of adult aging and induced positive and negative mood on planning

Changes in executive functions have been found in older adults and also in young adults experiencing positive or negative mood states. The current study investigated the hypothesis that older adults would show greater executive function impairment following mood induction than young adults. Ninety-six participants (half aged 19-37, half aged 53-80) completed a neutral, positive, or negative mood induction procedure, followed by the Tower of London planning task. Significant interactions were found between age and mood such that older adults showed greater planning impairment than young adults in both the positive and negative mood conditions. Emotionally salient events occurring before testing may interfere with executive function in older adults.     

Age-related differences in semantic priming: evidence from event-related brain potentials

Hasher and Zacks (1988) suggested that aging may affect processes involved in the inhibition of irrelevant information during language processing. Our experiment tested this hypothesis using the N400 event-related brain potential in a priming paradigm and assessed whether older subjects could benefit from the constraints of a sentence context. Twenty older (63 to 88 years) and 20 young (19 to 29 years) subjects read sentences and word pairs. Each final word varied on the degree of relatedness to the preceding context, with some being highly related (BC), moderately related (R), or unrelated (U). Younger subjects showed the expected N400 effect gradient (U > R > BC) in both the sentence and word-pair contexts, while older adults showed no discrimination between the conditions (U = R = BC) for the sentence and limited discrimination (U > BC) for the word pairs. These results support the inhibition-deficit hypothesis, whereby older adults fail to inhibit related items in working memory, and suggest that older adults do not benefit from the constraints of a sentence context.     

Infants' understanding of object-directed action

When and in what ways do infants recognize humans as intentional actors? An important aspect of this larger question concerns when infants recognize specific human actions (e.g. a reach) as object-directed (i.e. as acting toward goal-objects). In two studies using a visual habituation technique, 12-month-old infants were tested to assess their recognition that an adult's reach is directed toward its target object. Infants in the experimental condition were habituated to a display in which an actor reached over a wall-like barrier with an arcing arm movement, to pick up a ball. After habituation infants saw two test displays, for which the barrier was removed. In the direct test event the actor reached directly for the ball, the arm tracing a visually new path, but the action consistent with attempting to reach for the object as directly as possible. In the indirect test event the actor traced the old path, reaching over in an arc, even though the wall was no longer present. This arm movement was identical to that in habituation but no longer displayed a reach going directly to its object. In a control condition infants saw the same movements but in a situation with no goal-object. In the experimental conditions, with a goal object present, infants looked longer at the indirect test event in comparison to the direct test event. In the control conditions infants looked equally at both indirect and direct test events. We conclude that sensitivity to human object-directed action is established by 12-month-olds and compare these results to recent findings by [Gergely, G., Nadasdy, Z., Csibra, G., & Biro S. (1995). Taking the intentional stance at 12 months of age. Cognition, 56, 165-193] and [Woodward, A. (1998). Infants selectively encode the goal object of an actor's reach. Cognition, 69, 1-34].     

The effects of universal pre-K on cognitive development

In this study of Oklahoma's universal pre-K program, the authors relied on a strict birthday eligibility criterion to compare "young" kindergarten children who just completed pre-K to "old" pre-K children just beginning pre-K. This regression-discontinuity design reduces the threat of selection bias. Their sample consisted of 1,567 pre-K children and 1,461 kindergarten children who had just completed pre-K. The authors estimated the impact of the pre-K treatment on Woodcock-Johnson Achievement test scores. The authors found test impacts of 3.00 points (0.79 of the standard deviation for the control group) for the Letter-Word Identification score, 1.86 points (0.64 of the standard deviation of the control group) for the Spelling score, and 1.94 points (0.38 of the standard deviation of the control group) for the Applied Problems score. Hispanic, Black, White, and Native American children all benefit from the program, as do children in diverse income brackets, as measured by school lunch eligibility status. The authors conclude that Oklahoma's universal pre-K program has succeeded in enhancing the school readiness of a diverse group of children.     

Delayed attentional engagement in the attentional blink

Observers often miss the 2nd of 2 visual targets (first target [T1] and second target [T2]) when these targets are presented closely in time; the attentional blink (AB). The authors hypothesized that the AB occurs because the attentional response to T2 is delayed by T1 processing, causing T2 to lose a competition for attention to the item that follows it. The authors investigated this hypothesis by determining whether the AB is attenuated when T2 is precued. The results from 4 experiments showed that the duration and magnitude of the AB were substantially reduced when T2 was precued. The observed improvement in T2 report did not occur at the expense of T1 report, suggesting that processing of T1 was already completed or was at least protected when the cue was presented. The authors conclude that, during the AB, there is a delay between detection and the selection of target candidates for consolidation in short-term memory.     

Auditory saltation in the vertical midsagittal plane

Auditory saltation is an illusion in which a train of clicks, the first half of which is presented at one location and the other half of which is presented from a second location, is perceived as originating not only from the anchor points, but also from locations between them. That is, intermediate members of the series of clicks have their spatial locations systematically misperceived. In the present study, auditory saltation was examined for the first time in the vertical midsagittal plane. Subjects rated the perceived continuity of motion for 8-click trains systematically varied in inter-click interval (ICI), direction of motion (up, down), and trial type ('saltation' versus 'real' motion). In all listeners, saltation stimuli supported robust saltation, but only for trials with ICIs less than about 120 ms. Real motion was rated as continuous for all ICIs. These data indicate that the auditory-saltation illusion can exploit monaural stimulus cues for source location in the generation of the illusory motion percept.     

Relationships between physical activity and motor skills in middle school children

The purpose of this study was to examine the relationships between physical activity measured as pedometer steps and performance on three motor skill tests. A secondary purpose was to determine if middle school children are meeting the recommendation for the number of daily steps. A sample (n =217) of 6th, 7th and 8th grade students participated. Each subject wore a Digi-Walker pedometer for three consecutive days. Subjects additionally recorded their pedometer steps in two 45 min.-physical education classes. There were strong significant correlations between daily steps taken by boys and girls, pedometer steps during physical education class and the AAHPERD Passing Test and the Bass Stick Balance. Similar correlations were weaker for the Side-Step Agility Test. Multivariate analysis of variance was utilized to examine variability of the three skills test by sex and year in school. Differences between students in Grades 7 and 8 on the AAHPERD Passing Test were significant. In addition, significant differences between daily pedometer steps and steps during physical education between Grades 6 and 7 were observed. Boys and girls had similar means on the AAHPERD Passing Test and Bass Stick Balance Test, but not on the Side-Step Agility Test. Scores on the three movement skills tested in this study were not strongly related to physical activity of the entire sample. Steps taken by middle school children appear not to be related to these measures of motor skills.     

Effects of 3-D complexity on the perception of 2-D depictions of objects

In a recent study, Pelli (1999 Science 285 844-846) performed a set of perceptual experiments using portrait paintings by Chuck Close. Close's work is similar to the 'Lincoln' portraits of Harmon and Julesz (1973 Science 180 1194-1197) in that they are composite images consisting of coarsely sampled, individually painted, mostly homogeneous cells. Pelli showed that perceived shape was dependent on size, refuting findings that perception of this type is scale-invariant. In an attempt to broaden this finding we designed a series of experiments to investigate the interaction of 2-D scale and 3-D structure on our perception of 3-D shape. We present a series of experiments where field of view, 3-D object complexity, 2-D image resolution, viewing orientation, and subject matter of the stimulus are manipulated. On each trial, observers indicated if the depicted objects appeared to be 2-D or 3-D. Results for face stimuli are similar to Pelli's, while more geometrically complex stimuli show a further interaction of the 3-D information with distance and image information. Complex objects need more image information to be seen as 3-D when close; however, as they are moved further away from the observer, there is a bias for seeing them as 3-D objects rather than 2-D images. Finally, image orientation, relative to the observer, shows little effect, suggesting the participation of higher-level processes in the determination of the 'solidness' of the depicted object. Thus, we show that the critical image resolution depends systematically on the geometric complexity of the object depicted.     

Scented memories of literature

This study examined the effects on recall of story details of congruity or incongruity between the hedonic valence of literary texts and odours inhaled while reading them. During the reading session, 24 undergraduates (12 males and 12 females) read two passages involving positive subject matter and two with negative subject matter while sniffing pleasant or unpleasant odours in a within-subject fully counterbalanced design. Subjects rated their experience of each text on eleven 7-point scales. During the test session 48 hours later, subjects read a two-word title associated with each of the passages and inhaled the odour that was paired with it in the reading session. They also rated their experience on six of the scales that had been used during the reading session. Results showed that hedonic congruence between the passage and the odour fostered enhanced recall during the test session. The combination of positive subject matter and positive odour was reflected in more accurate recall of character details, while pairing negative subject matter and negative odour resulted in more accurate recall of setting details. Regression analysis showed that overall recall accuracy was increased by identifying with the characters in the stories and for passages that were found pleasing and personally meaningful. Consistent with the literature on implicit learning involving odours, recall accuracy varied inversely with perceived odour intensity. Implicit learning involving odours and literary passages is therefore fostered by unity in the reading experience.