Producing high-dimensional semantic spaces from lexical co-occurrence

A procedure that processes a corpus of text and produces numeric vectors containing information about its meanings for each word is presented. This procedure is applied to a large corpus of natural language text taken from Usenet, and the resulting vectors are examined to determine what information is contained within them. These vectors provide the coordinates in a high-dimensional space in which word relationships can be analyzed. Analyses of both vector similarity and multidimensional scaling demonstrate that there is significant semantic information carried in the vectors. A comparison of vector similarity with human reaction times in a single-word priming experiment is presented. These vectors provide the basis for a representational model of semantic memory, hyperspace analogue to language (HAL).     

Sleep arrangements and night waking at 6 and 12 months in relation to infants' stress‐induced cortisol responses

The objective of this short‐term longitudinal study was to examine the concurrent and prospective associations of infants' sleep arrangements and night waking with cortisol responses to an inoculation at 6 and 12 months, controlling for several key covariates. To our knowledge, this was the first study to concurrently and prospectively link proximity in sleep arrangements and night waking to physiological stress reactivity. A sample of 92 mother–infant dyads participated in the study when the infants were 6 and 12 months of age, although sample sizes were reduced for some analyses. Both proximal cosleeping arrangements and more frequent night wakings' were associated concurrently with an increased cortisol response to inoculations at both ages. Night waking at 6 months also was associated with a slightly increased cortisol response to inoculation at 12 months. Results aimed at exploring the direction of influence suggested that cosleeping and night waking may influence infant stress physiology rather than the reverse. Adaptive and maladaptive implications of infants' nocturnal experiences and greater stress‐induced cortisol responses are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Changes in the incidental context impacts search but not loading of the motor buffer

During a retention test, a change in the nature of the incidental contextual information present during training can have a deleterious impact on response selection by not activating particular subsets of information in memory that help direct the retrieval process. The present experiment addressed whether a change in the incidental context also impacted the completion of processes associated with loading and searching the motor buffer during motor programming. A self-select paradigm was used to describe the planning and execution of one- and four-element sequences that consisted of short and long duration key-presses. During a test phase following training, changes in the incidental contextual information impeded the search of the motor buffer. However, loading specific timing information into the motor buffer was unaffected by shifts in contexts. These data support the contention that contextual information plays a fundamental role in a broad array of movement-planning operations that involve search and retrieval type activity.     

A computational approach to modeling population differences

Four experiments were conducted to determine whether the Hyperspace Analogue to Language (HAL) model of semantic memory could differentiate between two different populations. An analysis of the differences in densities (or average distances between word neighbors in semantic space) in HAL matrices—generated from text corpora derived from younger and older adults—confirmed that HAL was able to distinguish between the two age groups. This difference was again detected when structured interview data were used to build the corpora. A third experiment, designed to test the specificity of HAL in detecting differences between groups, did not detect any difference in the densities of the memory representations when older adults generated both the test corpora. The final experiment, conducted on the language of adults with Alzheimer’s and normal adults, again demonstrated that HAL could discriminate between the two populations. These results suggest that HAL is capable of modeling, on the basis of changes in mean density, some of the differences between populations without modifying the model itself but, rather, by changing the text corpus from which the model creates its representations in semantic space.     

“All I remember is the black eye”: A distinctive facial feature harms eyewitness identification

Many crimes occur in which a perpetrator has a distinctive facial feature, such as a tattoo or black eye, but few eyewitness identification (ID) studies have involved such a feature. We conducted an experiment to determine how eyewitness ID performance is impacted by a distinctive facial feature, and how police could deal with this issue. Participants (N = 4,218) studied a target face with or without a black eye, and later viewed a simultaneous photo lineup either containing the target or not. For those who saw a target with a black eye, this feature was either replicated among all lineup members or was removed. The black eye harmed empirical discriminability regardless of replication or removal, which did not differ. However, participants responded more conservatively when the black eye was removed, compared to replication. Lastly, immediate confidence was consistently indicative of accuracy.     

A Follow-up Study of Group Psychotherapy Patients

The usefulness and efficacy of group psychotherapy with a variety of adolescent problems has been well documented. Far less has been reported with respect to group treatment approaches for youthful depressives, however. Currently available treatments lack specificity, making replication difficult. Additionally, they often focus on a narrow range of deficit areas rather than addressing the multifaceted range of dysfunction characteristic of depression in adolescents. This paper critically reviews the available literature on group treatments with depressed adolescents, explores some of the shortcomings inherent in these reports, and suggests alternatives for future group protocols. It is proposed that subsequent interventions be manualized and that they target affective, behavioral, and cognitive aspects of adolescent depression. Such an approach would be more amenable to scientific investigation, replication, and comparison with alternative approaches.     

Higher-order semantic structures in an African Grey parrot’s vocalizations: evidence from the hyperspace analog to language (HAL) model

Previous research has described the significant role that social interaction plays in both the acquisition and use of speech by parrots. The current study analyzed the speech of one home-raised African Grey parrot (Psittacus erithacus erithacus) across three different social contexts: owner interacting with parrot in the same room, owner and parrot interacting out of view in adjacent rooms, and parrot home alone. The purpose was to determine the extent to which the subject’s speech reflected an understanding of the contextual substitutability (e.g., the word street can be substituted in context for the word road) of the vocalizations that comprised the units in her repertoire (i.e., global co-occurrence of repertoire units; Burgess in Behav Res Methods Instrum Comput 30:188–198, 1998; Lund and Burgess in Behav Res Methods Instrum Comput 28:203–208, 1996). This was accomplished via the human language model hyperspace analog to language (HAL). HAL is contextually driven and bootstraps language “rules” from input without human intervention. Because HAL does not require human tutelage, it provided an objective measure to empirically examine the parrot’s vocalizations. Results indicated that the subject’s vocalization patterns did contain global co-occurrence. The presence of this quality in this nonhuman’s speech may be strongly indicative of higher-order cognitive skills.     

Prenatal maternal anxiety and early childhood temperament

The consequences of exposure to prenatal maternal anxiety for the development of child temperament were examined in a sample of 120 healthy, 2-year-old children. Prenatal maternal state and pregnancy-specific anxiety (PSA) were measured five times during pregnancy, and maternal state anxiety was measured again at 2 years post partum. Child temperament was measured at 2 years using the Early Childhood Behavior Questionnaire. The relationship between the trajectory of maternal anxiety across gestation and negative affectivity was evaluated using hierarchical linear growth curve modeling. Higher maternal PSA between 13 and 17 weeks of gestation was associated with increased negative temperament in the children. This association could not be explained by postnatal maternal anxiety, demographic, or obstetric factors. Prenatal maternal state anxiety was not associated with child temperament. These findings demonstrate that PSA early in gestation has a distinctive influence on the developing fetus.     

Perceived partner support in pregnancy predicts lower maternal and infant distress

Maternal postpartum emotional distress is quite common and can pose significant risk to mothers and infants. The current study investigated mothers' relationships with their partners during pregnancy and tested the hypotheses that perception of prenatal partner support is a significant predictor of changes in maternal emotional distress from midpregnancy to postpartum, and contributes to maternal ratings of infant distress to novelty. Using a prospective longitudinal design, 272 adult pregnant women were interviewed regarding their partner support, relationship satisfaction, and interpersonal security (attachment style and willingness to seek out support), and they completed standardized measures of prenatal symptoms of depression and anxiety (distress). At 6 to 8 weeks' postpartum, mothers reported these symptoms again and completed measures of their infants' temperament. Structural equation modeling (SEM) was used to test direct and indirect contributions of partner support, relationship satisfaction, and interpersonal security to maternal and infant postpartum distress. Mothers who perceived stronger social support from their partners midpregnancy had lower emotional distress postpartum after controlling for their distress in early pregnancy, and their infants were reported to be less distressed in response to novelty. Partner support mediated the effects of mothers' interpersonal security and relationship satisfaction on maternal and infant outcomes. A high-quality, supportive partner relationship during pregnancy may contribute to improved maternal and infant well-being postpartum, indicating a potential role for partner relationships in mental health interventions, with possible benefits for infants as well.