Brightness for different surround conditions: the effect of transient glare

We measured the effect of a transient glare source on t heperceived brightness of astandard luminance (L(STD)) patch (0.5 cd/m2) as a function of the surround luminance (Ls). In the experiment, both increment and decrement stimuli were dependent on the value of the Ls (0.01, 0.2, 0.4, 0.6, 0.8, 1.0, 1.5, or 2.0 cd/m2). We adopted a magnitude comparison paradigm using constant stimuli to determine the test matching luminance (L(M)). When L(S) was lower than the luminance of the patch, which corresponds to increments, LM was lower than L(STD), and this effect was highest for the lowest L(S). There was a small but noticeable cusp as increments shifted to decrements. As L(S) increased further (i.e., as the decrement grew), L(M) flattened out below L(STF). The overall pattern of results could be interpreted in terms of the concept of contrast brightness, with consideration of the intrinsic differences in brightness evaluations between decrements and increments.     

The Effects of Hippocampal and Area Parahippocampalis Lesions in Pigeons: II. Concurrent Discrimination and Spatial Memory

Two experiments were conducted to examine the effects of bilateral hippocampus (Hp) and area parahippocampalis (APH) lesions in pigeons on the acquisition of a visual and spatial task. In Experiment 1, pigeons were trained on three successive six-pair concurrent discrimination tasks, each using a novel set of stimuli. There was no difference between control unoperated pigeons and Hp-APH pigeons in terms of the number of sessions required to learn either the first, second, or third concurrent discrimination task. In Experiment 2, the same pigeons were trained on an open-field spatial task similar in many ways to the radial-arm maze task used with rats. In contrast to the absence of impairments on the visual concurrent discrimination task, pigeons with Hp-APH lesions were severely impaired on the acquisition of the spatial task. These findings support the view that the Hp-APH in pigeons is important for the processing of spatial, rather than visual information.     

Age-related trends in Stroop and conflicting motor response task findings.

Inhibition problems are reportedly at the heart of several childhood pathologies and learning disorders, but few instruments are available for their in-depth investigation. The main aim of the present study was to investigate the development of a capacity to inhibit automatic responses in young and middle childhood. For this purpose, 100 children between 6 and 11 years old were administered two tests that measure executive inhibition: an animal Stroop task (in a paper-and-pencil version of the computerized original proposed by Wright and colleagues in 2003) and a conflicting motor response task. Our results indicate that performance clearly improves in both tests during the course of a child's development and the data obtained with the paper-and-pencil animal Stroop task overlap with those obtained with the computerized version. When the task calls for a stronger inhibitory control (the incongruent situation in the Stroop task and in the opposite condition in the conflicting motor response test) the trend of the response times is less homogeneous, peaking in the youngest and oldest age brackets considered. The positivity and significance of the correlation coefficients between the two tests also suggest that the two measures are tapping cognitive abilities that are developing in a parallel fashion.     

Interpreting visual preferences in the visual paired-comparison task

Performance on the visual paired-comparison (VPC) task has typically been interpreted with E. Sokolov's (1963) comparator model of the orienting response; novelty preferences are interpreted as evidence of retention, whereas null preferences are interpreted as evidence of forgetting. Here the authors capitalized on the verbal nature of human adults to clarify the interpretation of visual preferences in VPC performance. In 2 experiments, adults were tested on either the VPC task or a forced-choice recognition task after delays of 3 min to 12 months. In Experiment 1, adults tested on the VPC task exhibited novelty preferences after short delays, null preferences after intermediate delays, and familiarity preferences after long delays. In Experiment 2, adults tested on the forced-choice recognition task exhibited high levels of accuracy irrespective of delay, but the latency with which they recognized the stimuli increased systematically over the retention interval. These data are inconsistent with a simple Sokolovian interpretation of VPC performance and instead suggest that memory may be expressed as a novelty preference, null preference, or familiarity preference depending on the accessibility of the representation.