Human Signs Research Articles

Signs in Which Handshape and Hand Orientation Are Either Not Visible or Are Only Partially Visible: What Is the Consequence for Lexical Recognition?

We present the results of an experiment on lexical recognition of human sign language signs in which the available perceptual information about handshape and hand orientation was manipulated. Stimuli were videos of signs from Sign Language of the Netherlands (SLN). The videos were processed to create four conditions: (1) one in which neither handshape nor hand orientation could be observed, (2) one in which hand orientation could be extracted but not handshape, (3) one in which an approximation of the handshape could be seen, and (4) one where the video was unmodified. In general, recognition of the signs was almost impossible in the first two conditions, while condition 3 showed a rise in recognition rate to about 60 percent However, some signs were recognized well even in conditions 1 and 2. Their success rate cannot be linked to a single sign property but seems to be due to a combination of factors. In general, handshape information appears more salient for resolving the lexical meaning of a sign than hand orientation.

Technology for supporting web information search and learning in Sign Language

Sign Languages (SL) are underrepresented in the digital world, which contributes to the digital divide for the Deaf Community. In this paper, our goal is twofold: (1) to review the implications of current SL generation technologies for two key user web tasks, information search and learning and (2) to propose a taxonomy of the technical and functional dimensions for categorizing those technologies. The review reveals that although contents can currently be portrayed in SL by means of videos of human signers or avatars, the debate about how bilingual (text and SL) versus SL-only websites affect signers’ comprehension of hypertext content emerges as an unresolved issue in need of further empirical research. The taxonomy highlights that videos of human signers are ecological but require a high-cost group of experts to perform text to SL translations, video editing and web uploading. Avatar technology, generally associated with automatic text-SL translators, reduces bandwidth requirements and human resources but it lacks reliability. The insights gained through this review may enable designers, educators or users to select the technology that best suits their goals.

On Signature Invariants for Effective Motion Trajectory Recognition

Motion trajectory can be an informative and descriptive clue that is suitable for the characterization of motion. Studying motion trajectory for effective motion description and recognition is important in many applications. For instance, motion trajectory can play an important role in the representation, recognition and learning of most long-term human or robot actions, behaviors and activities. However, effective trajectory descriptors are lacking and most reported work just uses motion trajectory in its raw data form. In this paper, we propose a novel motion trajectory signature descriptor and study its rich descriptive invariants which benefit effective motion trajectory recognition. These invariants are key measures of the flexibility and effectiveness of a descriptor. Substantial descriptive invariants can be deduced from the proposed trajectory signature, which is attributed to the computational locality of the signature components. We first present the signature definition and its robust implementation. Then the signature's invariants are elaborated. A non-linear inter-signature matching algorithm is developed to measure the signature's similarity for trajectory recognition. Experiments are conducted to recognize human sign language, in which both synthetic and real data are used to verify the signature's invariants, and to illustrate the effectiveness in the signature recognition.

Cross-fostered chimpanzees modulate signs of American Sign Language

Evolutionary and developmental (Evo-Devo) biologists study the interaction between genetic endowment and developmental environment (Lewontin, 2001; Robert, 2004). Cross-fostering is a powerful tool for studying Evo-Devo. Chimpanzees lived under conditions very similar to the conditions of human children with human foster families who used American Sign Language (ASL) exclusively in their presence. In this environment, cross-fostered chimpanzees acquired and used signs as human children do. Intensive analyses of extensive video records of casual conversation show that Tatu at 46–48 months directionally modulated action signs to indicate actor and instrument as human signers do. Tatu directionally modulated action signs in responses to Wh-questions such as “Who?” but directional modulations failed to appear in responses to What Demonstrative questions such as “What that?” These results confirm and extend previous results for Dar at 37–48 months. Further analyses show that Tatu also quantitatively modulated all types of signs to indicate intensity as human signers do.

Cross-fostered chimpanzees modulate signs of American Sign Language

Evolutionary and developmental (Evo-Devo) biologists study the interaction between genetic endowment and developmental environment (Lewontin, 2001; Robert, 2004). Cross-fostering is a powerful tool for studying Evo-Devo. Chimpanzees lived under conditions very similar to the conditions of human children with human foster families who used American Sign Language (ASL) exclusively in their presence. In this environment, cross-fostered chimpanzees acquired and used signs as human children do. Intensive analyses of extensive video records of casual conversation show that Tatu at 46–48 months directionally modulated action signs to indicate actor and instrument as human signers do. Tatu directionally modulated action signs in responses to Wh-questions such as “Who?” but directional modulations failed to appear in responses to What Demonstrative questions such as “What that?” These results confirm and extend previous results for Dar at 37–48 months. Further analyses show that Tatu also quantitatively modulated all types of signs to indicate intensity as human signers do.

Vocal stimulation early in life and infant vocal responsiveness to mother vs. stranger: A curvilinear relationship

Ape language research presents us with a worthy and successful example of realist bootstrapping of theorizing and experimentation. In the 1940s, the Hayeses set out without a definition of language, merely taking it that it appeared in the normal maturation of the normal human in normal circumstances and so might appear in a chimpanzee similarly placed. The Gardeners, noting the chimpanzee's limited vocalizing apparatus, tried to show that a chimpanzee would develop language in the same way as the human child if only the language were a sign language. Meshing with research by Premack and Terrace, recent work on fluent human signers of American Sign Language has shown that while chimpanzees can be led to use a gestural pidgin-vocabulary to manipulate and socialize, they in no way develop linguistically as the human infant signer does. In terms of homology, a case can be made that the signing chimpanzees have little improved on the Hayeses' chimpanzee, who eventually vocalized five English words. What this stretch of interaction between theory and experiment bears out is the autonomy of the formal linguistic apparatus from other conceptual and perceptual capacities that we undoubtedly share with our primate cogeners.

The vindication of the language organ

Ape language research presents us with a worthy and successful example of realist bootstrapping of theorizing and experimentation. In the 1940s, the Hayeses set out without a definition of language, merely taking it that it appeared in the normal maturation of the normal human in normal circumstances and so might appear in a chimpanzee similarly placed. The Gardeners, noting the chimpanzee's limited vocalizing apparatus, tried to show that a chimpanzee would develop language in the same way as the human child if only the language were a sign language. Meshing with research by Premack and Terrace, recent work on fluent human signers of American Sign Language has shown that while chimpanzees can be led to use a gestural pidgin-vocabulary to manipulate and socialize, they in no way develop linguistically as the human infant signer does. In terms of homology, a case can be made that the signing chimpanzees have little improved on the Hayeses' chimpanzee, who eventually vocalized five English words. What this stretch of interaction between theory and experiment bears out is the autonomy of the formal linguistic apparatus from other conceptual and perceptual capacities that we undoubtedly share with our primate cogeners.