Evaluating the decay gradient for collinearity bias with lateral displacement from the axis of induction

The misperception of alignment which is found in many geometric illusions can be quantified using relatively simple stimulus configurations. Perceived collinearity of one segment (designated as the test segment) is biased by a second segment (designated as the induction segment), with the size of effect being a function of the relative angle between the two segments. The process can be described as angular induction. The strength of bias is greatest when the induction segment is centered at the tip of the test segment. Tong and Weintraub have reported that lateral displacement from the tip, i.e., at right angles to the axis of the induction segment, produces a sharp drop in the strength of effect. This decline is described as a decay gradient for the angular induction. One experiment replicates and provides better quantification of this decay gradient. Two other experiments examine the decay gradient using a pair of induction segments, one on each side of the tip of the test segment. Displacement of the segments (either in the same direction or in opposite directions) produces substantially the same gradient of effect. Therefore, previous evidence of tandem boosting of effect for segment pairs does not depend on collinearity among the stimulus components. Finally, a fourth experiment finds that an induction segment which is at a fixed position and orientation differentially affects the influence of a variable induction segment. At some angles the influence of the variable segment is augmented, and at others it is suppressed. These findings are discussed in a neuroreductionist context, and a simple model for angular induction is presented.     

Using the HOME inventory with infants in Costa Rica

It has been established through several decades of research that children's home environments significantly influence their development. Many researchers have also been interested in expanding research beyond indirect measures of the home environment, such as socioeconomic status, to help understand the nature of specific environmental mechanisms which influence early behavior and cognitive development. The Home Observation for Measurement of the Environment (HOME) Inventory was developed to meet these needs. Specifically, HOME measures the quality of stimulation in a child's early family environment. Almost all studies of the approach's reliability and validity have been conducted with US samples. HOME is, however, being used in other countries. The authors report their findings from a study of whether the psychometric properties of HOME based upon US samples parallel those found in Costa Rica, and whether HOME discriminates between Costa Rican environments with different associations to child health and development. Focus centers upon the infant/toddler version of the HOME Inventory. HOME data for 183 healthy Costa Rican infants were compared to the original HOME standardization sample from Little Rock, Arkansas. The study found the HOME Inventory to be helpful in identifying children at risk for delayed development in this Latin American sample. Lower HOME scores related to a shorter duration of breastfeeding and differentiated children with iron deficiency anemia in infancy, a condition associated with long-lasting developmental disadvantage.     

Session helpfulness and session evaluation in short‐term counselling

The relationship between perceived session helpfulness and session evaluation was examined in 11 dyads during eight sessions of short‐term counselling. Results based on the Session Evaluation Questionnaire (Stiles, 1980) showed that, for clients, while depth, arousal, and positivity correlated with perceived session helpfulness, only depth and positivity entered a stepwise regression, yielding a multiple correlation of 0.76. For counsellors, while depth and positivity correlated with session perceived helpfulness, only depth entered the stepwise regression analysis, with a correlation of 0.70. Session depth also consistently correlated with change in perceptions of helpfulness from one session to another. Clients had higher depth scores for sessions that both participants rated as helpful. They had lower depth scores for sessions rated as less helpful by both participants or for sessions where participants disagreed in their helpfulness ratings. The centrality of counselling depth in affecting experiences of counselling helpfulness is discussed.     

Selective mutism in children: A structural family therapy approach to treatment

When children refuse to speak in some social settings, but can understand and speak in other settings, the diagnosis of selective mutism must be considered. A review of the literature describes the disorder, the various types of mutism, and related family dynamics. A family systems approach to treatment using structural family therapy is suggested. The case history presented illustrates one type of mutism as well as the family rules and hierarchy which appeared to be maintaining it. Structural and strategic family systems theory techniques that were used to move the family toward resolution of this problem are discussed.Diane Wolf Tatem, MA, MS, completed graduate work in marriage and family therapy at New Mexico State University, Las Cruces, NM. She is employed at Life Management Center of El Paso's Child Development Services and also has a private practice in marriage and family therapy in El Paso, Texas. Robert L. DelCampo, PhD is a professor of family science at New Mexico State University and maintains a private practice with Associates for Marriage and Family Therapy in Las Cruces, NM. Please address all correspondence to Dr. DelCampo at Box 3470, New Mexico State University, Las Cruces, NM, 88003-3470.Appreciation is expressed to Dr. Charles Huber, New Mexico State University in Las Cruces, for his insightful critique of the final draft of this paper. This paper was presented at the Texas Association for Marriage and Family Therapy Annual Conference, January 25–29, 1995 in Dallas, TX.     

Book reviews

Integrative Psychological and Behavioral Science -     

Diaphragmatic spasm: A neglected cause of dyspnoea and chest pain

The study included 17 patients, 12 women and 5 men, with a recurrent symptom complex involving chest pain and dyspnoea characterized by inability to get a full breath. Some attacks had subsided spontaneously. Others had lasted hours or days. When examined by fluoroscopy during an attack, each subject was found to have a nearly maximally contracted (flat) diaphragm. In some of them the attack was promptly interrupted by a small intravenous injection of sodium amytal. In others it could be aborted by a conscious effort at full expiration. The syndrome associated with diaphragmatic spasm is discussed in comparison with other noncardiac sources of chest pain and dyspnoea.     

Classical geometric illusion effects with nonclassical stimuli: Angular induction from decomposing lines into point arrays

Angular induction is the process by which one line segment can bias judgment of orientation and/or collinearity of another segment, and it has been established that the magnitude of error is a determinate function of the relative angle between the two. We examined how these known relationships are affected by decomposing the induction segment into an array of scattered points. The bias that was produced by such arrays was found to be consistent with a formal model of angular induction, with the strength of the effect decreasing as the scatter among the points was increased. This decline in strength was almost linear with a logarithmic transform of the dimensions of the stimulus array. We also evaluated the hypothesis that the induction stimulus is detected by one or more channels—for example, neurons—for which the sensitivity profiles are modeled as Gabor wavelets. The change in induction strength with increasing point scatter was not predicted by a single width of channel. However, the combined activity of an ensemble of channels that differed in width did match the perceptual effects if one also stipulated that each channel would respond maximally to a fine-line stimulus.     

Perceptual invariance for stop consonants in different positions

The basis for the invariant perception of place of articulation in pre- and postvocalic stops was investigated using the selective adaptation paradigm. Experiments 1 and 2 considered the role of identical bursts, mirror-image formant transitions, and similar onset and offset spectra in the invariant perception of place of articulation in CV and VC stimuli, and Experiment 3 considered the importance of the second two cues in a VCV context. The results of these experiments suggest that, at the level of processing tapped by selective adaptation, neither identical bursts, mirror-image formant transitions, nor similar onset and offset spectra are the basis for the invariant perception of place of articulation in initial and final position. The vowel portion of an adapter was found to affect perception of the consonant portion of a stimulus, and the direction of this effect was predictable from the acoustic characteristics of the consonant and vowel. The implications of these findings for the nature of selective adaptation are discussed.