Serial learning by rhesus monkeys: II. Learning four-item lists by trial and error

Three rhesus macaque monkeys were trained to produce novel 4-item lists (A-->B-->C-->D) on which all items were displayed from the start of training. Subjects were previously trained to produce 4-item lists by adding one item at a time (A, A-->B, A-->B-->C, and A-->B-->C-->D; lists K. B. Swartz et al., 1991). Those lists could be mastered by responding to each new item last. To learn lists on which all items were displayed from the start of training, subjects had to recall the consequences of errors and correct responses to each item. Errors ended the trial; correct responses to A, B, or C allowed the trial to continue. A correct response to D produced food reward. Although the probability of executing a 4-item list correctly by chance was .04, each subject mastered 4 novel 4-item lists by trial and error. The ability of monkeys to use a trial-and-error strategy to learn novel lists provides a basis for studying the development of serial expertise in animals.     

Concordance Between Parent Reports of Children's Mental Health Services and Service Records: The Services Assessment for Children and Adolescents (SACA)

The concordance between parent reports of children's mental health services and medical and administrative service records were assessed in a field test of the Services Assessment for Children and Adolescents (SACA) interview instrument. Service use reports from primary caregivers, usually mothers, for their child's emotional or behavioral problems were compared against inpatient, outpatient, and school records in St. Louis, one of the pilot sites for the Multi-Site Study of Service Use, Need, Outcomes and Costs in Child and Adolescent Populations (UNOCCAP). A global any use service variable, comprised of inpatient, outpatient, and school reports, yielded an overall service use concordance kappa of .76 between parent reports and records. Parent reports of inpatient hospitalization services using the SACA yielded the highest agreement with medical records, with kappa statistics of 1.00 for use of any inpatient hospital care and for medication use. Parent reports of specific inpatient services concurred with medical records more moderately, yielding kappas from .50 to .66. Reports of any outpatient mental health services yielded variable rates of agreement, with kappas ranging from .67 for any use of outpatient care, to .66 for medication use, to negligible kappas for specific treatments. Parent reports of school services were weakly related to records for most services, except for moderate agreement (.48) on placement in special classrooms for emotional or behavioral problems. Family burden or impact discriminated more powerfully than other variables between respondents who concurred with records and those who did not.     

Imaging high-resolution structure of GFP-expressing neurons in neocortex in vivo

To detect subtle changes in neuronal morphology in response to changes in experience, one must image neurons at high resolution in vivo over time scales of minutes to days. We accomplished this by infecting postmitotic neurons in rat and mouse barrel cortex with a Sindbis virus carrying the gene for enhanced green fluorescent protein. Visualized with 2-photon excitation laser scanning microscopy, infected neurons showed bright fluorescence that was distributed homogeneously throughout the cell, including axonal and dendritic arbors. Single dendritic spines could routinely be resolved and their morphological dynamics visualized. Viral infection and imaging were achieved throughout postnatal development up to early adulthood (P 8-30), although the viral efficiency of infection decreased with age. This relatively noninvasive method for fluorescent labeling and imaging of neurons allows the study of morphological dynamics of neocortical neurons and their circuits in vivo.     

The development of area discrimination and its implications for number representation in infancy

This paper investigates the ability of infants to attend to continuous stimulus variables and how this capacity relates to the representation of number. We examined the change in area needed by 6-month-old infants to detect a difference in the size of a single element (Elmo face). Infants successfully discriminated a 1:4, 1:3 and 1:2 change in the area of the Elmo face but failed to discriminate a 2:3 change. In addition, the novelty preference was linearly related to the ratio difference between the novel and familiar area. Results suggest that Weber's Law holds for area discriminations in infancy and also reveal that at 6 months of age infants are equally sensitive to number, time and area.     

The level of cholinergic nucleus basalis activation controls the specificity of auditory associative memory

Learning involves not only the establishment of memory per se, but also the specific details of its contents. In classical conditioning, the former concerns whether an association was learned while the latter discloses what was learned. The neural bases of associativity have been studied extensively while neural mechanisms of memory specificity have been neglected. Stimulation of the cholinergic nucleus basalis (NBs) paired with a preceding tone induces CS-specific associative memory. As different levels of acetylcholine may be released naturally during different learning situations, we asked whether the level of activation of the cholinergic neuromodulatory system can control the degree of detail that is encoded and retrieved. Adult male rats were tested pre- and post-training for behavioral responses (interruption of ongoing respiration) to tones of various frequencies (1-15 kHz, 70 dB, 2 s). Training consisted of 200 trials/day of tone (8.0 kHz, 70 dB, 2 s) either paired or unpaired with NBs (CS-NBs = 1.8 s) at moderate (65.7+/-9.0 microA, one day) or weak (46.7+/-12.1 microA, three training days) levels of stimulation, under conditions of controlled behavioral state (pre-trial stable respiration rate). Post-training (24 h) responses to tones revealed that moderate activation induced both associative and CS-specific behavioral memory, whereas weak activation produced associative memory lacking frequency specificity. The degree of memory specificity 24 h after training was positively correlated with the magnitude of CS-elicited increase in gamma activity within the EEG during training, but only in the moderate NBs group. Thus, a low level of acetylcholine released by the nucleus basalis during learning is sufficient to induce associativity whereas a higher level of release enables the storage of greater experiential detail. gamma waves, which are thought to reflect the coordinated activity of cortical cells, appear to index the encoding of CS detail. The findings demonstrate that the amount of detail in memory can be directly controlled by neural intervention.     

Dissonance and importance: attitude change effects of personal relevance and race of the beneficiary of a counterattitudinal advocacy

The authors asked or instructed White college students to write an essay advocating a large tuition hike to increase scholarships for either students in general or Black students (yielding low or high racial symbolism, respectively) that would take effect in the near or far future (yielding high or low personal relevance, respectively). Especially when high-choice participants wrote highly compliant (i.e., unqualified) essays, attitude change was greater when the advocacy had either high (vs. low) personal relevance or high (vs. low) racial symbolism. Yet there was no attitude change when both symbolism and relevance were high. They may increase dissonance by making the dissonant elements more important and numerous. The coupling of relevance and symbolism, however, may link the attitude so strongly to personal values and self-concept that attitude change becomes untenable as a mode of dissonance reduction.     

The influence of provocateurs' emotion displays on the social information processing of children varying in social adjustment and age

This study examined the effect of provocateurs' emotion displays on first through fourth graders' social information processing (SIP). Rating and nomination sociometric techniques were used to identify rejected-aggressive, rejected-nonaggressive, average-nonaggressive, and popular-nonaggressive groups. Children viewed videotaped ambiguous provocation situations in which provocateurs' emotion displays were varied systematically. After each vignette, children's recall of story details, attribution of intent, and problem-solving responses were obtained. Half of the children were randomly assigned to a condition where they were asked directly about provocateurs' emotions, and the remaining children were not asked about provocateurs' feelings. Results revealed both developmental and social adjustment differences in SIP. In addition, provocateurs' emotion displays and asking versus not asking about those displays influenced multiple aspects of SIP.     

College students, tattoos, and sexual activity

This research examined the association of having a tattoo and engaging in premarital sexual intercourse. Data gathered from a convenience sample of 450 college students indicated that tattooed respondents were substantively and significantly more likely to be sexually active than nontattooed college students. Tattooed men became sexually active at a significantly earlier age than nontattooed men but no such difference was found between tattooed and nontattooed college women.     

Constant capacity in an immediate serial-recall task: a logical sequel to Miller (1956)

We assessed a hypothesis that working memory capacity should include a constant number of separate mental units, or chunks (cf. Miller, 1956). Because of the practical difficulty of measuring chunks, this hypothesis has not been tested previously, despite wide attention to Miller's article. We used a training procedure to manipulate the strength of associations between pairs of words to be included in an immediate serial-recall task. Although the amount of training on associations clearly increased the availability of two-item chunks and therefore the number of items correct in list recall, the number of total chunks recalled (singletons plus two-word chunks) appeared to remain approximately constant across association strengths, supporting a hypothesis of constant capacity.     

Kicking coordination captures differences between full-term and premature infants with white matter disorder

This study explores the relation of white matter disorder (WMD) to intralimb coordination patterns in premature infants with very low birth weight (VLBW). We specifically measured the temporal-spatial characteristics of intralimb coordination patterns of the legs. Three groups of infants were compared at one month corrected age (CA): 10 premature infants born VLBW and WMD (PTWMD), 10 premature infants born VLBW without WMD (PT) and 10 full term infants (FT). Using kinematic variables, we discriminate among VLBW infants with WMD from the two comparison groups. Infants born with WMD maintain patterns of tight coupling among leg joints (all flexion or all extension) while PT and FT term infants have begun to decouple leg joints by this age (combinations of flexion with extension). The coupling pattern is captured through joint correlations, discrete relative phase, and phase plane portraits. The PTWMD infants also demonstrate aberrant patterns of coordination evident through both temporal and spatial characteristics of the kicks. This is the first evidence that movement disorder associated with brain lesions can be identified and quantified with kinematic variables as early as one month of age.