Hemispatial asymmetries in judgment of stimulus size

Recent research has demonstrated a leftward bias in judgments of size. In the present experiments, hemispatial size bias was measured through simultaneous presentation of a circle and an ellipse varying in horizontal or vertical extent. A consistent leftward bias of horizontal size judgments (but not vertical) was obtained; at the point of subjective equality, the width of the objects that were presented in left hemispace was smaller than the width of the objects that were presented in right hemispace. These data suggest that the horizontal extent of stimuli appear larger in left hemispace than in right hemispace. Results also indicated that symmetrical stimulus presentation, with respect to the vertical meridian, is required for the bias to emerge. Furthermore, increasing or decreasing stimulus eccentricity weakened the effect. Attenuation of this bias upon the manipulation of parameters indicates that this phenomenon is context specific and is affected by similar parameters that are known to influence the magnitude of error in pseudoneglect.     

Moral judgment in relation to behavioral and cognitive disorders in adolescents

The capacity for formulating moral judgments shown by 20 emotionally disturbed, cognitively delayed adolescents was related to their social behaviors as observed in a classroom situation. Adolescents reported by their teachers to be shy and submissive were less capable of reasoning about moral issues than were adolescents who were seen as more assertive and socially engaged. The level of moral judgment was not a function of intelligence or ability to understand concrete operations. The implication that social engagement is a critical determinant of moral judgment for these adolescents is discussed.     

Choice reaction and unequal stimulus frequencies in an absolute judgment situation

Previous investigators have reported discrepant results for Ss in a choice reaction time (CRT) situation when stimuli are not equi-probable. Sixty Ss participated in an absolute judgment CRT task under three conditions of equi-probable stimuli and three of unequally probable stimuli. The results indicate that previous findings may be determined by a threshold dependent upon the effect of unequal stimulus frequencies and the utilities of different response strategies.     

Choice reaction and unequal stimulus frequencies in an absolute judgment situation

Previous investigators have reported discrepant results for Ss in a choice reaction time (CRT) situation when stimuli are not equi-probable. Sixty Ss participated in an absolute judgment CRT task under three conditions of equi-probable stimuli and three of unequally probable stimuli. The results indicate that previous findings may be determined by a threshold dependent upon the effect of unequal stimulus frequencies and the utilities of different response strategies.     

Duration of visible persistence in relation to stimulus complexity

Visible persistence refers to the phenomenal impression that a stimulus is still present after its offset. A dispute exists whether visible persistence is due to temporal sluggishness in the visual pathway (neural hypothesis) or whether it is a byproduct of information-extraction processes under cognitive control (process hypothesis). This was investigated by manipulating stimulus complexity in five temporal integration experiments and one recognition memory experiment. According to the process hypothesis, complex stimuli should persist longer than simple stimuli because they require more information extraction. This prediction was not confirmed; in all six experiments, complexity was found to have no reliable effect on the duration of visible persistence. By contrast, and in accordance with earlier findings, complexity was shown to have a significant effect on a short-lived, nonvisible form of memory known as schematic persistence. This pattern of results supports two major conclusions: First, that the effects of complexity reported in earlier research were probably on schematic—rather than visible—persistence; and second, that visible persistence must be regarded as a residual neural trace of an extinguished stimulus, rather than as a byproduct of information-extraction processes.     

The relation between stimulus function and equivalence class formation

Fifty participants were exposed to a simple discrimination-training procedure during which six S+ functions were established for six arbitrary stimuli, and S- functions were established for a further six stimuli. Following this training, each participant was exposed to one of five conditions. In the S+ condition, participants were exposed to a stimulus equivalence training and testing procedure using only the six S+ stimuli as samples and comparisons. In the S+/S- condition, participants were exposed to the same training and testing sequence as in the S+ condition, the difference being that three S+ and three S- stimuli were used as sample and comparison stimuli, with each set of three corresponding to the trained equivalence relations. In the S+/S- mixed condition, the S+ and S- stimuli were assigned to their roles as samples and comparisons in a quasi-random order. In the S- condition, all six S- stimuli were used. The no-function condition served as a control condition and employed stimuli for which no stimulus-control functions had been established. The results showed that, on average, participants required more testing trials to form equivalence relations when the stimuli involved were functionally similar rather than functionally different. Moreover, participants required more test trials to form equivalence relations when novel arbitrary stimuli, rather than functionally distinct stimuli, were used as samples and comparisons. The speed of acquisition of stimulus equivalence was also related to the number of functionally similar stimuli established before training. These findings indicate a variety of ways in which the emergence of equivalence relations is affected by the functional classes in which the relevant stimuli participate.     

The effect of discrimination training on responses to a new stimulus

Most previous research on the effect of the duration of preceding discrimination training on responding to a new stimulus has measured the responding during extinction. To reduce effects originating in the extinction procedure itself, the present study assessed the effect of discrimination training on responses to a new negative stimulus added during continued discrimination training. Pigeons were given a new negative stimulus (blue key) after 0, 1, 3, or 9 days of discrimination training with a yellow key as the positive stimulus, and both a green key and a red key as negative. Fewer responses were made to the blue key when it was introduced after nine days of discrimination training than after less discrimination training. That effect of long discrimination training agrees with reported results from extinction tests. However, the effect of briefer discrimination training in the present study differed from reported results with extinction testing. It appears that testing during continued discrimination training eliminates a distortion present in extinction tests of the effect of discrimination training on responding to a new stimulus.     

The effect of simultaneous and sequential presentation of stimulus dimensions on absolute judgment accuracy

The effects of spatial stimulus repetition, sequential stimulus repetition, spatially separated dimensional redundancy, and sequentially presented dimensional redundancy on absolute judgment accuracy of hue and brightness were compared. Two exposure durations, 0.1 and 2.0 sec, were used. While spatial repetition did not improve accuracy for either dimension, the sequential repetition of brightness produced a small increase in accuracy. The spatial presentation of correlated values of both dimensions increased accuracy only at the 2.0-sec duration. The sequential presentation of both dimensions increased accuracy, but only at the 2.0-sec duration was this gain substantial and greater than that provided by the sequential repetition of brightness alone.     

Short-term memory in deaf and hearing children in relation to stimulus characteristics

Experiment 1 examined short-term memory with a serial probe task in 20 younger (mean age: 6 years, 3 months) and 20 older (mean age: 8 years, 8 months) deaf children. Four sets of stimuli were used: familiar animals, unfamiliar nonsense forms, fingerspelled letters, and lower-case print. In contrast to earlier research with hearing children, strong primacy effects were found with all stimuli at both ages, with frequent gestural and/or oral labeling but little cumulative rehearsal evident. To determine whether results were uniquely tied to deafness, identical procedures were used in Experiment 2 with 20 younger (4 years, 9 months) and 20 older (5 years, 10 months) hearing children. Again, overt activity was common, with strong primacy effects on animals and nonsense forms in the older group and on animals in the younger group. Contrasts between present and earlier findings suggest the need to consider the degree to which stimulus labels are overlearned, the role of nonverbal mediators in rehearsal, and the effects of changing educational experiences.     

Duration of visible persistence in relation to stimulus complexity.

Visible persistence refers to the phenomenal impression that a stimulus is still present after its offset. A dispute exists whether visible persistence is due to temporal sluggishness in the visual pathway (neural hypothesis) or whether it is a byproduct of information-extraction processes under cognitive control (process hypothesis). This was investigated by manipulating stimulus complexity in five temporal integration experiments and one recognition memory experiment. According to the process hypothesis, complex stimuli should persist longer than simple stimuli because they require more information extraction. This prediction was not confirmed; in all six experiments, complexity was found to have no reliable effect on the duration of visible persistence. By contrast, and in accordance with earlier findings, complexity was shown to have a significant effect on a short-lived, nonvisible form of memory known as schematic persistenc. This pattern of results supports two major conclusions: First, that the effects of complexity reported in earlier research were probably on schematic--rather than visible--persistence; and second, that visible persistence must be regarded as a residual neural trace of an extinguished stimulus, rather than as a byproduct of information-extraction processes.     

Awareness of time distortions and its relation with time judgment: a metacognitive approach

The perception of time cannot be reduced to a simple percept produced by an internal clock. The aim of the present study was therefore to investigate the role of the individual consciousness of time on temporal judgments. In the present study, the participants' awareness of attention-related time distortions was assessed using a metacognitive questionnaire. The participants were also required to verbally judge a series of stimulus durations in a single or a dual task condition. The results revealed that time was underestimated in the dual task compared to the single task. However, the accuracy of time judgments improved in line with the participants' individual awareness of attentional time distortion: The more aware they were of the role of attention in time perception, the lower the time distortions they exhibited. Conscious awareness of time therefore plays a role in the accuracy of the time judgments made by human beings.