Time perception and the internal clock: Effects of visual flicker on the temporal oscillator

Abstract

Our ability to estimate time intervals has sometimes been attributed to a biological source of temporal information. A model for a temporal oscillator that provides such information has recently been described (Treisman, Faulkner, Naish & Brogan, 1990). This predicts that an imposed stimulus rhythm at certain frequencies may interfere with the temporal oscillator so as to alter its frequency. This interference would cause perturbations in temporal judgements at certain frequencies of the imposed rhythm. The pattern of interference would depend on the frequency at which the temporal oscillator runs, and so would contain information about the oscillator frequency. Evidence for such a pattern was found when auditory clicks at different rates were presented concurrently with time intervals whose durations subjects estimated. The present study examines whether a similar interference pattern can be obtained if visual flicker is substituted for auditory clicks. On each trial, flicker was presented at a rate between 2.5 and 17.5 Hz, concurrently with a time interval to be estimated. A pattern of increased estimates at some rates and decreased estimates at others was obtained. This pattern showed similarities to interference patterns obtained using auditory clicks. This provides evidence that the entrainment of the internal clock predicted by the model can also be produced by visual inputs. Other theoretical implications are discussed.     

The abilities of children with mental retardation to remember personal experiences: implications for testimony

Investigated the abilities of children with mental retardation to remember the details of a personally experienced event. A simulated health check was administered to 20 children with mental retardation and 40 normally developing children, half matched on mental age (MA) and half matched on chronological age (CA) with the children with mental retardation. The children's memory was assessed immediately after the health check and 6 weeks later. Overall, the children with mental retardation accurately recalled the health check features, provided detail, and resisted misleading questions about features that did not occur. The group with mental retardation performed similarly to the MA matches on virtually all of the memory variables. The children with mental retardation performed worse than the CA matches on most of the memory variables, although they were able to recall a similar number of features. The findings are discussed in terms of the ability of children with mental retardation to provide accurate testimony.     

Prehension movements in a patient (AC) with posterior parietal cortex damage and posterior callosal section

Prehension movements of the right hand were recorded in a right-handed man (AC), with an injury to the left posterior parietal cortex (PPC) and with a section of the left half of the splenium. The kinematic analysis of AC's grasping movements in direct and perturbed conditions was compared to that of five control subjects. A novel effect in prehension was revealed--a hemispace effect--in healthy controls only. Movements to the left hemispace were faster, longer, and with a smaller grasp aperture; perturbation of both object position and distance resulted in the attenuation of the direction effect on movement time and the time to velocity peak, with a reverse pattern in the time to maximum grip aperture. Nevertheless, the correlation between transport velocity amplitude and grasp aperture remained stable in both perturbed and non-perturbed movements, reflecting the coordination between reaching and grasping in control subjects. In contrast, transport and grasp, as well as their coordination in both direct and perturbed conditions, were negatively affected by the PPC and splenium lesion in AC, suggesting that transport and grasp rely on two functionally identifiable subsystems.     

Attentional load associated with performing and stabilizing a between-persons coordination of rhythmic limb movements

This study addressed the issue of intentional stabilization of between-persons coordination patterns (in-phase/isodirectional and anti-phase/non-isodirectional) and the attentional cost incurred by the nervous system in maintaining and further stabilizing these coordination patterns. Five pairs of participants performed in-phase and anti-phase interpersonal coordination patterns in dual-task conditions (coordination+RT task). Results showed that: (1) isodirectional pattern (in-phase) was more stable than non-isodirectional pattern (anti-phase), (2) both iso- and non-isodirectional pattern were stabilized intentionally, (3) RT was lower for the isodirectional pattern (i.e., the most stable), and (4) attentional manipulation led to a trade-off between pattern stability and RT performance. These results suggest that performing between-persons coordination patterns incurs a central cost that depends on the coupling strength between the limbs. These findings are consistent with the previous studies in intrapersonal coordination.     

Survey of advantages obtained by judoka in competition by level of practice

In judo, placing the opponent in a situation of uncertainty requires the mastery of several throws. French young judoka learn, respectively, 10, 9, and 8 throws to earn yellow, orange, and green belts. These techniques allow throwing down a judoka in several directions (backward, forward, left and right). To see what happens in competition 82 judoka were observed during regional competitions. The average number of matches was 3.3 +/- 0.5. The average number of successful attack directions was 2.8 +/- 1.3 for 8 children at orange to green belt level; 2.1 +/- 0.7 for 11 children at blue belt level; 2.2 +/- 0.8 for 17 children at brown belt level; 2.8 +/- 0.9 for 20 cadets at brown to black belt level, 2.6 +/- 1.1 for 10 juniors at brown to black belt level, and 3.3 +/- 0.9 for 16 seniors at black belt level. These scores for children with blue and brown belts were significantly different (p=.02) from those of seniors with black belts. Such results imply a nonlinear progression between the technical level (represented by the belt) and the capacity to create uncertainty (the ability to throw down the opponent with at least three techniques in three different directions). Judo is a sport of slow technical maturation; it requires this adaptation before its mastery in competition.     

Psychometric properties of the temperament and character inventory-revised (TCI-R) in a Belgian sample

The Temperament and Character Inventory (TCI; Cloninger, Przybeck, Svrakic, & Wetzel, 1994) is a self-questionnaire developed to assess the 7 dimensions of personality described by Cloninger et al. (1994) with a total of 29 subscales. In 1999, a revised version was proposed by Cloninger (TCI-R). In this study, we present psychometric properties of the TCI-R from 958 French-speaking participants of Belgium. Women exhibited higher scores for harm avoidance, reward dependence, and cooperativeness dimensions. The proposed factorial structure of 4 temperament dimensions and 3 character dimensions was confirmed. The TCI-R inventory had good test-retest reliabilities as well as good alpha coefficients. The addition of 3 new subscales to the original scale for Persistence has produced a very reliable dimension in the TCI-R.     

Psycholinguistic norms for action photographs in French and their relationships with spoken and written latencies

A set of 142 photographs of actions (taken from Fiez & Tranel, 1997) was standardized in French on name agreement, image agreement, conceptual familiarity, visual complexity, imageability, age of acquisition, and duration of the depicted actions. Objective word frequency measures were provided for the infinitive modal forms of the verbs and for the cumulative frequency of the verbal forms associated with the photographs. Statistics on the variables collected for action items were provided and compared with the statistics on the same variables collected for object items. The relationships between these variables were analyzed, and certain comparisons between the current database and other similar published databases of pictures of actions are reported. Spoken and written naming latencies were also collected for the photographs of actions, and multiple regression analyses revealed that name agreement, image agreement, and age of acquisition are the major determinants of action naming speed. Finally, certain analyses were performed to compare object and action naming times. The norms and the spoken and written naming latencies corresponding to the pictures are available on the Internet (http://www.psy.univ-bpclermont.fr/~pbonin/pbonin-eng.html) and should be of great use to researchers interested in the processing of actions.     

The metrics of spatial distance traversed during mental imagery

The authors conducted 2 experiments to study the metrics of spatial distance in a mental imagery task. In both experiments, participants first memorized the layout of a building containing 10 rooms with 24 objects. Participants then received mental imagery instructions and imagined how they walked through the building from one room to another. The authors manipulated Euclidean distance involved in these imaginary motions: Spatial distance measured in centimeters on the layout was either short or long. Independently, they varied categorical distance: The motions led through one room or two rooms. The time needed to imagine motions and response times to test probes indicated that both Euclidean distance and categorical distance affected mental imagery. The authors discuss the new finding of categorical distance effects in mental imagery and relate the results to earlier failures to find Euclidean distance effects in formally equivalent studies of narrative comprehension.