A simple method for performing t tests of the differences between means of independent groups, matched groups, and paired observations is presented and illustrated. The method is especially appropriate where data are collected simultaneously on a large number of dependent variables. Statistical tables are provided which markedly reduce the number of calculations to be performed. The method provides a clearcut way of graphically representing t test data relative to chosen significance levels.
not employed under the no-knowledge condition. For both treatments reacciontime increased systematically with time on task, the greatest amount of change occurring under the no-knowledge condition. In addition, reaccion-rime was a decreasing function of length of interstimulus interval. The findings of the no knowledge portion of the forementioned study are atypical in two respects. Whereas the slope of the linear function relating reaction-time (msec.) to task duration (5-min. blocks) was 11.93, those of one earlier (McCormack, 1958) and rwo later srudies (McCormack, 1960; McCormack & Prysiazniuk, 1961) were 5.46, 4.75, and 3.79, respectively. Also atypical was the finding that reaction-time was a decreasing funccion of length of interstimulus interval since, in each of the three other investigations, an invariant relation was reported. Thus the major conclusions of the scudy employing the 10 females as Ss, especially the no-knowledge but probably the knowledge porcion as well, are highly questionable. The presenc experiments were therefore designed with the purpose of re-exploring the effects on reactiontime of knowledge of results of performance. METHOD S's task was to depress a microswitch as fast as possible each time light from a 15-w bulb was seen through an aperture 1/2 in. in diamecer. The duration of the light was 100 msec. and the apermre was placed at a distance of 7 fr. from S. Reaction-time was recorded by a Hunter Klockounter while the duration of the light was conuolled by a silent timer. A second timer enabled E, who was located in an adjacenc room, to determine whether or not S had responded within a 2-sec. period. In the event of a failure to respond the light was presented 'The research reported in this paper was supported by 3 grant-in-aid from the Associate Committee on Experimental Psychology of the National Research Council, Canada (Grant APBT-40).
Pc1s (continuous pulsations) within the geomagnetic field, whose durations are about 30 minutes but which can reoccur several times nightly, are observed during periods when global geomagnetic activity is very low (less than 10 nT). The hypothesis that these 0.2 to 5 Hz synchronized micropulsations or hydromagnetic emissions might stimulate physical chemical cascades within the brain that precipitate the sudden death in infants was tested by correlational analysis for a two-year period (1960-1961) for Ontario. Results were consistent with the hypothesis that the monthly incidences of these unexpected deaths, pcl micropulsations and geomagnetic activity less than 10 nT displayed a shared source of variance. Implications are discussed.
This study investigated stress symptoms before and after the September 11, 2001 terrorist attack on the World Trade Center. Responses to the Smith Stress Symptoms Inventory were compared for Chicago area college students assessed 1 to 5 weeks after 9/11 (n=149) and a comparable sample tested up to 5 months prior to 9/11 (n=320). Post-9/11 participants scored higher on Attention Deficit. Contrary to prior research, post-9/11 participants did not score higher on distress, including Worry, Autonomic Arousal/Anxiety, Striated Muscle Tension, Depression, and Anger. It is suggested that those indirectly exposed to a terrorist attack may display traditional symptoms of distress and arousal (as suggested by previous research). Later symptoms of attention deficit and distancing may emerge. This work was based on independent pre- and post-9/11 samples and must be replicated longitudinally as a test-retest to draw conclusions regarding change over time.
This study investigated whether stress symptoms related to attention deficit previously found for a sample (n= 149) of Chicago-area college students 1 to 5 weeks after the September 11th attacks were present in a comparable sample (n = 129) 12 to 14 months later. As hypothesized, the later participants had a significantly lower mean score on the scale, Attention Deficit of the Smith Stress Symptoms Inventory, than a different group of participants tested immediately after the attacks. Mean Attention Deficit scores for groups after one year and immediately before September 11th (n=320) did not differ statistically. Findings are consistent with the interpretation that elevations in scores on Attention Deficit immediately after September 11th were indeed associated with the catastrophic attacks and not artifacts of time of examination. Consistent with previous research with this inventory, disaster-related traumatic stress scores are lower over time, although here no control group was included.
Based on visual inspection of data, reinforcement procedures, namely, use of verbal praise and verbal praise plus token exchange, were at least mildly influential in improving performance of 5 youth with moderate mental retardation compared to their initial performance without reinforcers. These findings suggest specific reinforcement may improve the time for aerobic activity by adolescents with moderate mental retardation.
Human equilibrium was measured during exposure to continuous and intermittent 1000-Hz tones presented both asymmetrically (one ear) and symmetrically (both ears). Intermittency combined with asymmetry produced greater decrements in equilibrium than either variable alone. The results are interpreted as a possible demonstration of acoustic stimulation of the vestibular system.
Thresholds for pressure pain were tested in 64 adult human subjects (age: M=22.0 yr., SD=7.5). The subjects were young adults drawn from a student population. They were divided into two groups of men and two groups of women, with 16 participants in each group. A female experimenter tested one group of men and a male experimenter tested the other group. The women were tested in a similar way by an experimenter of the same sex for one group and the opposite sex for the other group. The two experimenters were dressed in a manner that emphasised their gender roles. The men tested by a female experimenter showed a higher average pain threshold than the men tested by a male experimenter, but there was no difference in the average pain thresholds of the two groups of women.
The odor of 2-heptanone was delivered by a precision olfactometer to five Ss using five methods of single-sample presentation of concentrations: (1) randomized, (2) sequential-down, (3) sequential-up, (4) constant stimulus—10 samples, and (5) constant stimulus—100 samples. Lowest thresholds were obtained with method (3) and the highest threshold resulted from method (2). Large variations in individual sensitivities between Ss were observed, precluding averaging of data in the constant stimulus methods. The latter were not suitable for measuring thresholds. No decrease in sensitivity due to fatigue or adaptation was noted in the 100-sample presentation; however, significant differences were found between the statistical errors of the first and second kind. When two odorous samples were presented concurrently within a series, a larger number of correct responses were obtained than when an air blank preceded the presentation of the odor, suggesting physical and/or psychological carry-over of stimulus. Specific modifications of the constant-stimulus method are discussed.
One of the most widely reported developmental deficits associated with autism is difficulty perceiving and expressing emotion appropriately. Brain activation associated with performance on a new task, the Emotional Congruence Task, requires judging affective congruence of facial expression and voice, compared with their sex congruence. Participants in this pilot study were adolescents with normal IQ (n = 5) and autism or without (n = 4) autism. In the emotional congruence condition, as compared to the sex congruence of voice and face, controls had significantly more activation than the Autism group in the orbitofrontal cortex, the superior temporal, parahippocampal, and posterior cingulate gyri and occipital regions. Unlike controls, the Autism group did not have significantly greater prefrontal activation during the emotional congruence condition, but did during the sex congruence condition. Results indicate the Emotional Congruence Task can be used successfully to assess brain activation and behavior associated with integration of auditory and visual information for emotion. While the numbers in the groups are small, the results suggest that brain activity while performing the Emotional Congruence Task differed between adolescents with and without autism in fronto-limbic areas and in the superior temporal region. These findings must be confirmed using larger samples of participants.
Does consciousness have a spatial "location" that can be scientifically investigated? Using a novel phenomenological method, when people are encouraged to explore the question introspectively they not only can make sense of the idea of their consciousness being "located," but will readily indicate its exact position inside the head. The method, based on Francisco J. Varela's work, involves a structured interview led by an expert mediator in which preliminary questions are asked of untrained volunteers about the location of objects and body parts, and then they are questioned about the location from which they are experiencing these objects. 83% of volunteers located with confidence a precise position for the I-that-perceives in the temporal area of the head centred midway behind the eyes. The same results were obtained with blind subjects (congenitally or later) and with non-Westerners. The significance of this subjective source of the experience of the location of perception is discussed linking it to neurological correlates of self-referred conscious activities and of conscious awareness in memory. Further investigations are suggested with trained volunteers and with individuals with psychiatric disorders.
The purpose of this study was to assess stability of manipulative behavior across time. 29 infants were seen at both 9 and 9.5 mo.; 20 of these infants were seen again at 12 mo. At each visit the infants were presented several objects for familiarization and tested for response to discrepant objects. Each trial was scored for the duration of looking, rotating the object, fingering, mouthing, and banging, the frequency of transferring the object from hand to hand, and the frequency of dropping, throwing and pushing the object away. Analysis of the data yielded moderate to high correlations between 9 and 9.5 mo. for all but one behavior. Correlations between 9 and 12 mo. were in the same range for most of the behaviors. On the test trials, there were fewer significant correlations. When the behaviors were separated into exploratory and nonexploratory categories, there was more stability for the nonexploratory behaviors; summary scores for both were concurrently related to Bayley Mental Development Index at 12 mo., but in opposite directions. The results suggest that there is stability in some manipulative behaviors, and further, that it is useful to conceptualize two types of manipulative behavior.
An analysis of the relationship of reading problems to language habits, PMA and the group Bender-Gestalt test was made for 750 children, ages 10 and 11, who represent 90% of all children born on Kauai, Hawaii in 1955. The percentage of reading problems increased from 1 out of 6 children in the above average to 1 out of 2 children in the below-average SES groups. 88% of the children with reading problems came from homes in which Pidgin English was frequently spoken. Children with reading problems had significantly lower mean scores on all PMA scores than successful readers. Factor V predicted reading grade and STEP reading test scores as well as PMA IQ and better than any other PMA factor. The incidence of reading problems increased with error scores on the group Bender-Gestalt test, but the majority of children with reading problems had adequate Bender-Gestalt reproductions. Most poor B-G reproductions were found among children of low and below average intelligence. The addition of the group Bender-Gestalt error score to the PMA IQ or Factor V did not improve the prediction of reading grade or reading test results.
Of 655 neuropsychological referrals who were asked to draw a clock and set the hands at "10 after 11," 9% set the hands at "10 to 11." This low base rate of occurrence suggests the error was not highly sensitive to neurological impairment or diagnostically specific.
This study examined growth rates in running speed and vertical jump among middle school children. 45 boys and 31 girls ages 11-13 years were tested on running speed and vertical jump three times (September, February, and May) during the school year. Hierarchical linear modeling was used to estimate initial status and growth rates for the entire sample (base model) and the association of running and vertical jump with height, weight, and sex (conditional model). Positive overall growth rates were found for both running speed and vertical jump. Increased heightand weight at the time of measurement were not significantly associated with growth rate for running. The growth rate for vertical jump was positively associated with height but unrelated to increased weight. Boys showed steeper growth rates than girls in jumping. No sex differences were found in running speed for either initial status or in growth rate. Furthermore, these results suggest highly variable rates of physical maturation but no general period of 'adolescent awkwardness'.
Impulsiveness is increasingly gaining attention as a potential risk factor for various mental disorders. Until now, there have been German instruments that allowed for assessing adolescents' self-reported impulsiveness multi-dimensionally. The present study examined the German version of the Barratt Impulsiveness Scale-11 (BIS-11) for adolescents. The instrument was completed by 659 adolescents ages 10 to 20 years; 98 were retested after 6 months. Items showed adequate psychometric properties. An exploratory factor analysis identified three factors that showed slightdifferences from the initial questionnaire proposed by Barratt. The factors showed low to moderate intercorrelations, satisfactory internal consistency (dependent on factor), and were stable over time. Convergent validity was ascertained, and the item pool showed sufficient power to discriminate adolescents with symptoms of attention deficit hyperactivity disorder and those with loss of eating control from healthy adolescents. Findings suggest that the German BIS-11 is appropriate for reliable investigation of impulsiveness in adolescents. Future research should examine sensitivity as a screening tool, as well as sensitivity to change.
The concurrent and content validity of the Rey-Osterrieth Complex Figure Test and the Beery Developmental Test of Visual-Motor Integration-Third Revision were investigated through correlational analysis. 432 children, ages 6 to 11 years, were administered both tests. Across age groups participants performed better on both measures, providing support for the similarity of the measures and their sensitivity to the development of visuomotor integration. Although analysis indicated considerable overlap in the content of the two scales, the shared variance ranged from 7% to 31%, depending on the age of the child. The Rey-Osterrieth figure is composed of overlapping squares, rectangles, triangles, and various other shapes. Given this complex combination, scores on this test reflect the examinees' visual organization and motor planning skills. On the other hand, the Beery test consists of a series of shapes which progress from simple figures to more complex ones. Because the figures become more difficult to copy, the score on this test reflects the examinees' developmental level of visuomotor ability. Despite these differences in test stimuli and interpretation of performance, the present study showed considerable shared variance in the scores of the examinees who took both tests. Finally, local norms for the Rey-Osterrieth figure using the scoring approach of E. M. Taylor (1959, adapted from Osterrieth, 1944) and including standard scores are presented for children ages 6 to 11 years.
Corsi's block-tapping test and WISC-R were given to 1122 children from 11 to 16 years of age. Corsi's raw scores were transformed into standard scores like those for the WISC-R subtests. Reliabilities, standard score equivalents of raw scores, correlations with scores on WISC-R subtests, scales and factor scores are presented. A Principal Factor analysis of intercorrelations for Corsi's test and WISC-R subtests shows a three-factor solution with Corsi's test loading on the Third Factor. Results agree with Wielkiewicz's (1990) hypothesis about the construct underlying WISC-R Third Factor as "executive" and short-term memory processes.
One issue in the development of narrative comprehension is whether cMdren initially process information at a low level, developing later the ability to build up higher units of organisation (4, 5), or whether they learn first to identify the main ideas of a passage and become increasingly able to subsume less structurally important units under them later in development (1, 3). These approaches may be described as 'bottom-up' and 'top-down' development, respectively. The present study compares the patterns of narrative recall by adults and 11-yr.-old children: taking adults' recall frequencies as an index oE the structural importance of story constituents, top-down development between these ages would predict good over-all agreement on recall frequencies, especially for the more 'important' constituents. Two groups of subjects, 22 children (M age 10.7 yr.; SD: 0.4) and 54 undergraduate students, each received the same 225-word, 30-clause narrative (passage 1A from Cornish, 2), chosen to be equally acceptable to the two age groups. Subjects were read the passage once and asked to write out as much of it as they could remember; they were discouraged from deliberate memorisation. Reproductions were scored for the number of original clauses recalled, after Cornish (2). The mean number of clauses recalled per subject was 17.9 (SD: 4.5) for the children and 23.5 (SD: 4.3) for the students. Recall probabilities were calculated for each clause separately for the two groups. There was a high product-moment correlation between the two sets of omission frequencies (fis = 0.715, p c ,001). However, inspection of the data suggested that the greatest agreement was on the most commonly recalled clauses. This was confirmed by comparing the correlations for the 15 most and 15 least frequently recalled clauses (by the adults' ratings), which were 0.429 (df= 13, p< .05) and 0.339 (df = 13, p = n.s.), respectively. Both the good agreement on the ordering of clauses by recall frequency and the greater agreement on the more frequently recalled clauses support 'top-down' development of narrative comprehension in the 11-yr. to adult age range. The children appear well able to identify structurally important narrative constituents but are less able to comprehend subsidiary material. Future work might look at younger children whose narrative development might proceed in a different manner.