On ‘there is’

Philosophical Studies -     

Stimulus factors in aversive controls: conditioned suppression after equal training to two stimuli

Pigeons trained to peck a key for food were periodically presented with tones ending with electrical shock until tone presentation consistently suppressed ongoing pecks. Shock was then discontinued and gradients of stimulus generalization were assessed by presenting tones with frequencies above, below, and at the frequencies of those used to develop conditioned suppression. When the training tones had frequencies at 670 and 1500 cps, resulting gradients were bi-modal with peak suppression at 670 and 1500 cps. Of the other test tones, 1000 cps produced the most suppression. When the training tones had frequencies at 450 and 2250 cps, bi-modal gradients were again obtained with peak suppression to the 450 and 2250 cps tones. Of the other test tones, 1000 cps produced the least suppression. These results support the hypothesis that generalized response tendencies summate.     

A cognitive development framework

Prominent stage theories of cognitive development show evidence of a structure in which each stage contains a number of subsidiary levels. Comparisons of the stages in these theories have commonly been made through the established links with stages of Piaget’s theory. In response to Kagan’s criticism of Piaget’s theory, features of these developmental theories were used in this paper as the basis for a general framework of interactive stages and levels of cognitive operations. Some implications of the proposed framework in relation to cognitive development theories and directions for further research are examined. Further application of this framework could help to identify commonalities in cognitive operations across different contents, contexts and cultures.     

Measuring the impact of informal caring

A factor-analysis of caregiving impact appraisals amongst a community-derived sample of informal carers of elderly people revealed two negative (care work strain and relationship dissatisfaction) and two positive (care work satisfaction and care lifestyle satisfaction) scales. Validity was assessed by means of concurrent correlations with levels of assistance with daily living tasks provided by carers and levels of behaviour problems exhibited by elderly dependents. Criterion validity was considered in relation to two important carer outcomes; willingness to care and a standardized measure of strain. Each of the four scales was significantly associated with concurrently assessed willingness to care. Care work strain and relationship dissatisfaction were associated with concurrently measured strain symptomology. Evidence of 6-month predictive validity was obtained for the care work strain scale.     

Shape from stereo: A systematic approach using quadratic surfaces

We used quadratic shapes in several psychophysical shape-from-stereo tasks. The shapes were elegantly represented in a 2-D parameter space by the scale-independentshape index and the scale-dependentcurvedness. Using random-dot stereograms to depict the surfaces, we found that the shape of hyperbolic surfaces is slightly more difficult to recognize than the shape of elliptic surfaces. We found that curvedness (and indirectly, scale) has little or no influence on shape recognition.