Emergence of representation in drawing: The relation between kinematic and referential aspects

To identify and characterize early instances in which children attribute meaning to their drawings, scribbles of 2- to 3-year-olds were examined from kinematic and representational perspectives. Scribbles were shown to be composed of smooth-inertial and angular-intentional curves, the former revealing a systematic relation between curvature and speed (the 2/ 3 power law). Children tended to attribute a-posteriori representational meanings (e.g., an airplane) to angular curves and nonrepresentational meanings (e.g., a line) to smooth curves, that they have just finished drawing. They did not do so with reference to scribbles drawn by peers, by themselves in the past, or by the experimenter who imitated their scribbling. Children's attribution of representational meanings increased with age. The phenomenon studied was discussed as a possible precursor of preplanned representational drawing, indicating the child's awareness of the symbolic function of a line—standing for itself and signifying a referent.     

The coordination of limb movements with different kinematic patterns

The principles underlying the coordination of limb movements with different spatiotemporal features were explored. After an initial training session in which the same unidirectional movement had to be performed with both upper limbs, subjects attempted to coordinate two different movements in a second session, i.e., the learned unidirectional movement in the left limb and a new double reversal movement in the right limb. The findings uncovered a wide variety in patterns of interlimb dependence among and within subjects, going from a high degree of dependence to relative independence. The relationship between limbs was studied by means of a detailed analysis of the displacement and acceleration patterns and the electromyographic activity of the major muscles involved. The general underlying principle that appeared to account for the diversity in movement organization was this: higher independence between limb movements is achieved when subjects initiate the movements to be coordinated successively. This asynchrony in movement onset can possibly be viewed as an attempt to safeguard against interference.     

Recognition of self-generated actions from kinematic displays of drawing

Five experiments addressed the question of whether individuals can distinguish between self-generated and other-generated actions when seeing their visual effects. Each experiment consisted of a recording session in which participants drew familiar and unfamiliar characters without receiving visual feedback and a recognition session in which they provided self-or-other judgments (SOJs) to indicate whether a kinematic display reproduced the visual effects of their own actions. The main results were that self-generated and other-generated drawing can be distinguished, that the familiarity of character shapes does not influence the accuracy of SOJs, and that velocity information is crucial for the identification of self-generated drawing. The ability to determine authorship from kinematic displays of drawing provides evidence for the contribution of action-planning structures to perception.     

A note on the kinematcis of drawing movements in children

The relationship between instantaneous tangential velocity and radius of curvature (power 1/3) that is characteristic of adult subjects was found to be already present in children 3 to 11 years old. The correlation coefficient between these two parameters increases gradually with age without apparent discontinuities. However, even at the upper limit of the age range examined, the values are still lower than in the adults.     

Integrating situational probability and kinematic information when anticipating disguised movements

ObjectivesThe current study sought to examine the relative contributions of kinematic and situational probability information to anticipation using different levels of disguised kinematics. More specifically, it was tested whether the weighting of the informational sources (kinematic vs. probabilistic) shifts relative to the certainty of the available kinematic information.Design and MethodHuman-like avatars were generated performing penalty throws and displayed in a virtual reality environment. The ambiguity of the kinematic information available from the avatars was systematically manipulated using linear morphing between genuine and disguised throws. In a perceptual classification task, trained novice observers (N = 23) were asked to classify as quickly and accurately as possible whether observed throws were either genuine or disguised. In addition, information about the performer’s action preferences was also systematically manipulated by explicitly informing participants about the performer’s AP to disguise their throw (25%, 50%, and 75%).ResultsParticipants’ response behavior showed that observers relied more heavily on the probabilistic information when the kinematics were ambiguous. For the AP 25% condition, observers were more likely to report that ambiguous throws were genuine (p < 0.001), whereas they classified the ambiguous throws as being disguised in the AP 75% condition (p < 0.001).ConclusionFindings suggest that observers rely more strongly on non-kinematic (situational probability) information when the reliability of the observable movement kinematics becomes less certain.     

On the law relating processing to storage in working memory

Working memory is usually defined in cognitive psychology as a system devoted to the simultaneous processing and maintenance of information. However, although many models of working memory have been put forward during the last decades, they often leave underspecified the dynamic interplay between processing and storage. Moreover, the account of their interaction proposed by the most popular A. D. Baddeley and G. Hitch's (1974) multiple-component model is contradicted by facts, leaving unresolved one of the main issues of cognitive functioning. In this article, the author derive from the time-based resource-sharing model of working memory a mathematical function relating the cognitive load involved by concurrent processing to the amount of information that can be simultaneously maintained active in working memory. A meta-analysis from several experiments testing the effects of processing on storage corroborates the parameters of the predicted function, suggesting that it properly reflects the law relating the 2 functions of working memory.     

Directed movements and the body-proportion effect in preschool children's human figure drawing

Drawing a human figure involves mastery over complex planning problems. The variant forms which young children produce may be an index of these. The most common variant is the “tadpole figure” with arms seemingly on the head. It is known that children who spontaneously draw this variant will attach arms correctly to the trunk of an incomplete pre-drawn figure if the head is small, but will attach them to the head if that exceeds the trunk in size. The present study shows that this body-proportion effect cannot be reliably modified by directing the pen to the head or trunk for the purpose of drawing body-parts other than arms; and that the arms are much more subject to the effect than the legs, nose, navel or ears. Experimental analysis of drawing based on completion-tasks can in principle help to bring out, and put under stimulus-control, performance characteristics which cannot reliably be inferred from post-hoc inspection of spontaneous finished products.     

Comfortable synchronization of cyclic drawing movements with a metronome

Continuous circle drawing is considered a paragon of emergent timing, whereas the timing of finger tapping is said to be event-based. Synchronization with a metronome, however, must to some extent be event-based for both types of movement. Because the target events in the movement trajectory are more poorly defined in circle drawing than in tapping, circle drawing shows more variable asynchronies with a metronome than does tapping. One factor that may have contributed to high variability in past studies is that circle size, drawing direction, and target point were prescribed and perhaps outside the comfort range. In the present study, participants were free to choose most comfortable settings of these parameters for two continuously drawn shapes, circles and infinity signs, while synchronizing with a regular or intermittently perturbed metronome at four different tempi. Results showed that preferred circle sizes were generally smaller than in previous studies but tended to increase as tempo decreased. Synchronization results were similar for circles and infinity signs, and similar to earlier results for circles drawn within a fixed template (Repp & Steinman, 2010). Comparison with tapping data still showed drawing to exhibit much greater variability and persistence of asynchronies as well as slower phase correction in response to phase shifts in the metronome. With comfort level ruled out as a factor, these differences can now be attributed more confidently to differences in event definition and/or movement dynamics.     

Effect of postural instability on drawing errors in children: a synchronized kinematic analysis of hand drawing and body motion

To investigate the role that postural stability plays in fine motor control, we assessed kinematics of the head, shoulder, elbow, and the pen during an accuracy drawing task in 24 children. Twelve children were classified into an accurate drawing (AD) group and 12 children into an inaccurate drawing (ID) group based on a manual dexterity task from the movement assessment battery for children [Henderson, S. E., & Sugden, D. A. (1992). Movement assessment battery for children. London: Psychological Corporation.]. Their parents completed a questionnaire to assess children's inattention, hyperactivity, and impulsivity. An electromagnetic tracking system was used to monitor 3-D kinematic data of the body parts, while 2-D kinematic data of pen movement was simultaneously collected from a computer digitizer tablet. If a sudden body motion (1cm/s) occurred within a time window from one second prior to the onset of the drawing error to the end of the error, we considered that the error coincided with the extraneous body movement. For each drawing trial, the coincidence rate was computed as (number of coincidences)/(number of errors). The ID group had a significantly higher coincidence rate of head and shoulder movements compared with elbow movements, whereas coincidence rates did not differ between the three body parts in the AD group. Parental ratings of children's behavioral ratings of inattention, hyperactivity, and impulsivity were not correlated with the coincidence rates. The results indicated that inaccurate drawing was a result of postural instability rather than fidgeting caused by inattention or hyperactivity/impulsivity.     

Relation between EMG activation patterns and kinematic properties of aimed arm movements

Aimed flexion movements of the arm of different amplitude and duration were studied. Velocity and acceleration traces of movements with equal duration but different amplitude were equal, apart from a scaling factor (ratio between movement amplitudes). After appropriate scaling, EMG activity of the first agonist burst for these movements superimposed. This was not true for EMG activity in the antagonist muscle. For movements with equal amplitude, but different duration, the time to peak acceleration was constant for all MT'. Except for this fact, traces of acceleration, velocity, and agonist activity following the time of peak acceleration were about equal after appropriate scaling in time and amplitude. The integral of EMG activity in the first agonist burst increased linearly with peak velocity. For the antagonist burst, the integrated EMG activity increased more than proportionally. During movements made as fast as possible, subjects used a different strategy by varying the duration of the accelerating phase for movements of different amplitude. Movement amplitude was achieved by adjusting the duration of the agonist burst and the onset time for the antagonist muscle. Amplitude of the antagonist burst was constant within a narrow range for movements of different amplitude. These results did not change when the inertial mass was doubled by loading the arm with an additional mass.     

Dissociation of explicit and implicit timing in repetitive tapping and drawing movements

Four experiments explored the hypothesis that temporal processes may be represented and controlled explicitly or implicitly. Tasks hypothesized to require explicit timing were duration discrimination, tapping, and intermittent circle drawing. In contrast, it was hypothesized that timing control during continuous circle drawing does not rely on an explicit temporal representation; rather, temporal control is an emergent property of other control processes (i.e., timing is controlled implicitly). Temporal consistency on the tapping and intermittent drawing tasks was related, and performance on both of these tasks was correlated with temporal acuity on an auditory duration discrimination task. However, timing variability of these 3 tasks was not correlated with timing variability of continuous circle drawing. These results support the hypothesized distinction between explicit and implicit temporal representations.     

Two-dimensional filtering,oriented line detectors,and figural aspects as determinants of visual illusions

Quantitative data of Müller-Lyer illusions from the literature were analyzed according to three different models. All three models predict the illusion effect, although with different magnitude and different parameter dependency. First, a filter model describing a certain amount of blurring of the retinal picture seems partly responsible for the observed illusion. With reasonable estimation of the filter constants, however, a sufficient magnitude of illusion cannot be obtained. A second model of oriented line or bar receptors is even less effective in explaining the observed length illusions. A third model, consisting of a size-constancy operator triggered by depth cues, may predict effects larger than actually observed. It is concluded that figural aspects such as depth-inducing cues are mainly responsible for the illusion effects observed in Müller-Lyer figures.     

Cultural differences in drawing movements between right-handed Japanese and German participants

Differences in drawing movements with the dominant and nondominant hands by 41 right-handed students from Japan (9 men, 12 women; M age = 20.3 yr., SD = 1.4) and Germany (13 men, 7 women; M age = 23.4 yr., SD = 3.0) were investigated. Participants were asked to use each hand to draw a circle, a pentagon, and a rhombus in one stroke. Analysis showed that Japanese participants drew a circle clockwise with the dominant right hand, starting from 6 or 7 o'clock on the face of a clock, while the German participants drew the circle counterclockwise, starting from 11 or 12 o'clock. Moreover, when drawing a pentagon and a rhombus with the right hand, Japanese participants drew counterclockwise from the top-center vertex, whereas almost half of German participants drew clockwise from the left side and others drew counterclockwise from the top-center vertex. Using the left hand, no significant difference was found in starting positions or directionality. Cultural differences in the starting positions and directionality when using the dominant right hand probably reflect the influence of writing habits on the drawing movement of the dominant hand.     

A developmental study of the relationship between geometry and kinematics in drawing movements.

Trajectory and kinematics of drawing movements are mutually constrained by functional relationships that reduce the degrees of freedom of the hand-arm system. Previous investigations of these relationships are extended here by considering their development in children between 5 and 12 years of age. Performances in a simple motor task--the continuous tracing of elliptic trajectories--demonstrate that both the phenomenon of isochrony (increase of the average movement velocity with the linear extent of the trajectory) and the so-called two-thirds power law (relation between tangential velocity and curvature) are qualitatively present already at the age of 5. The quantitative aspects of these regularities evolve with age, however, and steady-state adult performance is not attained even by the oldest children. The power-law formalism developed in previous reports is generalized to encompass these developmental aspects of the control of movement.