Colour specificity in episodic and in perceptual object recognition with enhanced colour impact

In three experiments we investigated the perceptual specificity of explicit (old-new object recognition) and implicit memory (word-picture matching) for colour. In order to enhance the impact of colour on processing, we increased the number of colours per object and we impaired shape information. We presented multicoloured pictures (Experiment 1), blurred and partially occluded pictures (Experiment 2) and coloured line drawings in visual noise (Experiment 3). Experiments 1 and 2 had an intentional study phase; the study phase of Experiment 3 was an incidental colour or category naming task. Changing colour from study to test always had negative effects on episodic recognition although colour was irrelevant. In contrast, in the matching task old pictures were generally matched faster than new ones independent of their colour congruence. In Experiment 3, an additional small advantage of congruent colours and of semantic processing occurred. We conclude that two different memory representations contribute to these tasks. Changes of an achromatic, more abstract representation, that is used in normal object recognition, and a representation of the specific exemplar that includes colour. This latter token is used in episodic recognition as well as in unusual perceptual tasks (Experiment 3).     

A study of retrieval processes in action memory for school-aged children: the impact of recall period and difficulty on action memory

ABSTRACT

Research in action memory for adults has shown that enacted encoding is not only retrieved more frequently but is also faster in comparison to verbal encoding. The aim of this study was to investigate retrieval processes in terms of recall period and recall difficulty for different encoding conditions in school-aged children (8-, 10-, 12-, 14-years old). The participants studied verbal tasks, subject-performed tasks and experimenter-performed tasks, and received immediate and final free-recall tests. The results revealed that older children not only outperformed younger children in terms of accuracy but also outpaced them in all recall periods. Moreover, recalls of subject-performed tasks and experimenter-performed tasks were better and faster compared with verbal encoding on both types of recall test, by increasing throughout the recall periods. These results are discussed in terms of memory strategies and information processing methods. Pedagogic implications for the use of action memory in children's learning are also considered.     

Ideational action impairments in Alzheimer's disease

We report data from a group of patients with mild Alzheimer's disease on a range of tasks requiring either stored semantic knowledge about objects (e.g., naming object use) or the execution of action to objects (e.g., miming and using objects). We found that the patients were impaired at miming in response to objects, even when they could describe the object's function. On the other hand, copying gestures was not impaired relative to naming gestures, indicating that an ideomotor deficit in action execution, per se, was unlikely to explain the impairments in object use. We suggest instead that the patients had an impairment in stored motor programmes for action, over and above their deficits in semantic knowledge. Despite this, the patients were better at using than at miming to objects, consistent with the view that proprioceptive input (when using objects) can directly constrain selection of the appropriate motor programme for action.     

Visual illusions affect both movement planning and on-line control: a multiple cue position on bias and goal-directed action

Over the last decade, there has been an interest in the impact of visual illusions on the control of action. Much of this work has been motivated by Milner and Goodale's two visual system model of visual processing. This model is based on a hypothesized dissociation between cognitive judgments and the visual control of action. It holds that action is immune to the visual context that provides the basis for the illusion-induced bias associated with cognitive judgments. Recently, Glover has challenged this position and has suggested that movement planning, but not movement execution is susceptible to visual illusions. Research from our lab is inconsistent with both models of visual-motor processing. With respect to the planning and control model, kinematic evidence shows that the impact of an illusion on manual aiming increases as the limb approaches the target. For the Ebbinghaus illusion, this involved a decrease in the time after peak velocity to accommodate the 'perceived' size of the target. For the Müller-Lyer illusion, the influence of the figure's tails increased from peak velocity to the end of the movement. Although our findings contradict a strong version of the two visual systems hypothesis, we did find dissociations between perception and action in another experiment. In this Müller-Lyer study, perceptual decisions were influenced by misjudgment of extent, while action was influenced by misjudgment of target position. Overall, our findings are consistent with the idea that it is often necessary to use visual context to make adjustments to ongoing movements.     

Distant Causation in <Emphasis Type="Italic">C</Emphasis>+

The action language C+ of Giunchiglia, Lee, Lifschitz, McCain and Turner is a high-level, logical formalism for the representation of domains involving action and change. However, one cannot directly express relationships which hold between states more than one time-step distant, or even say that one action determines another at the next time. We present C+_timed, a generalization of C+ which removes these limitations. As for C+, translations to the language of causal theories are given. We also define a new kind of transition system called a ‘run system’ to provide a graphical semantics. Finally, we show how domains involving prohibition and permission can be modelled, by incorporating the ideas of another extension of C+.     

Catching and matching bars with different orientations

The hypothesis that perception enslaves action is examined by assessing whether systematic distortions in perceptual judgments are reflected by inaccuracies in catching. In the first experiment, participants had to align manually the orientation of a reference bar placed at different distances in the frontoparallel plane. In the second experiment participants had to catch differently orientated moving bars, which became invisible at different distances from the interception point. In the matching experiment, systematic errors in the alignment of orientation were found in particular for oblique orientations, the magnitude of which increased with increasing distance of the reference bar. The inaccuracies in the final hand orientation during the catching task, however, did not mirror this pattern of deviations. The findings are interpreted to be more consistent with recent views that vision for perception (i.e., matching) and vision for action (i.e., catching) are dissociated than with the view that perception enslaves action.     

The role of proprioception in action recognition

This study aimed at evaluating the role of proprioception in the process of matching the final position of one's limbs with an intentional movement. Two experiments were realised with the same paradigm of conscious recognition of one's own limb position from a distorted position. In the first experiment, 22 healthy subjects performed the task in an active and in a passive condition. In the latter condition, proprioception was the only available information since the central signals related to the motor command were likely to be absent. The second experiment was realised with a deafferented patient who suffers from a complete haptic deafferentation, including loss of proprioception. The results first argue in favour of a dominant role of proprioception in action recognition, but they also stress the possible role of central signals. The process of matching the final position of one's limbs with an intended movement and thus of action recognition would be achieved through a comparison process between the predicted sensory consequences of the action, which are stored in its internal model, and the actual sensory consequences of that action.     

Eighteen-month-olds integrate verbal cues into their action processing: Evidence from ERPs and mu power

Behavioral research has shown that infants use both behavioral cues and verbal cues when processing the goals of others’ actions. For instance, 18-month-olds selectively imitate an observed goal-directed action depending on its (in)congruence with a model’s previous verbal announcement of a desired action goal. This EEG-study analyzed the electrophysiological underpinnings of these behavioral findings on the two functional levels of conceptual action processing and motor activation. Mid-latency mean negative ERP amplitude and mu-frequency band power were analyzed while 18-month-olds (N = 38) watched videos of an adult who performed one out of two potential actions on a novel object. In a within-subjects design, the action demonstration was preceded by either a congruent or an incongruent verbally announced action goal (e.g., “up” or “down” and upward movement). Overall, ERP negativity did not differ between conditions, but a closer inspection revealed that in two subgroups, about half of the infants showed a broadly distributed increased mid-latency ERP negativity (indicating enhanced conceptual action processing) for either the congruent or the incongruent stimuli, respectively. As expected, mu power at sensorimotor sites was reduced (indicating enhanced motor activation) for congruent relative to incongruent stimuli in the entire sample. Both EEG correlates were related to infants’ language skills. Hence, 18-month-olds integrate action-goal-related verbal cues into their processing of others’ actions, at the functional levels of both conceptual processing and motor activation. Further, cue integration when inferring others’ action goals is related to infants’ language proficiency.     

Hierarchical growing grid networks for skeleton based action recognition

In this paper, a novel cognitive architecture for action recognition is developed by applying layers of growing grid neural networks. Using these layers makes the system capable of automatically arranging its representational structure. In addition to the expansion of the neural map during the growth phase, the system is provided with a prior knowledge of the input space, which increases the processing speed of the learning phase. Apart from two layers of growing grid networks the architecture is composed of a preprocessing layer, an ordered vector representation layer and a one-layer supervised neural network. These layers are designed to solve the action recognition problem. The first-layer growing grid receives the input data of human actions and the neural map generates an action pattern vector representing each action sequence by connecting the elicited activation of the trained map. The pattern vectors are then sent to the ordered vector representation layer to build the time-invariant input vectors of key activations for the second-layer growing grid. The second-layer growing grid categorizes the input vectors to the corresponding action clusters/sub-clusters and finally the one-layer supervised neural network labels the shaped clusters with action labels. Three experiments using different datasets of actions show that the system is capable of learning to categorize the actions quickly and efficiently. The performance of the growing grid architecture is compared with the results from a system based on Self-Organizing Maps, showing that the growing grid architecture performs significantly superior on the action recognition tasks.     

Integrating Social Science and Design Inquiry Through Interdisciplinary Design Charrettes: An Approach to Participatory Community Problem Solving

Interdisciplinary collaborations that aim to facilitate meaningful community outcomes require both the right mix of disciplinary knowledge and effective community participation, which together can deepen collective knowledge and the capacity to take action. This article explores three interdisciplinary design charrettes, intensive participatory workshops that addressed specific community problems and provided a context for integrating design and social science inquiry with local community knowledge. Evaluation data from the charrettes shed light on how students from the design and social science disciplines experienced the charrettes, and on their interactions with community members. Key advantages to this interdisciplinary, community-based collaboration included expanded knowledge derived from the use of multiple modes of inquiry, particularly the resulting visualization tools that helped community members understand local issues and envision novel solutions. Key drawbacks included difficulties in balancing the two disciplines, the tendency for social scientists to feel out of place on designers' turf, and the increased disciplinary and interpersonal conflicts arising from a more diverse pool of participants.