Variables underlying the recognition of random shapes

Speed of sorting decks of 32 cards with two alternative stimuli was measured. The stimuli were pairs of dots with attributes of distance between dots, angle of orientation of the pair, and position of the pair to the right or left of center. The attributes varied in relative discriminability and were used in all possible pair- and triple-correlated (redundant) combinations. Results showed an increase in speed of sorting with either an increase in discriminability or an increase in number of redundant attributes. It is argued that the increased speed with addition of redundant attributes is due both to a selective serial processing of attributes (requiring attribute separability) and to an increased discriminability with combined attributes (requiring attribute integrality).     

Immediate and delayed recognition of sequentially presented random shapes.

Two experiments tested whether short-term memory accounts for the recency effect observed with rapid sequential presentation of nonverbal stimuli. Four random shapes were presented sequentially (with no interstimulus interval) on each trial at rates of 150 msec, 250 msec, 500 msec, and 1,000 msec per stimulus. Subsequent recognition varied positively with exposure duration, ranging from 57% at 150 msec to 77% at 1,000 msec. Two serial position effects were observed: a slight decrease in recognition accuracy for the first stimulus in each sequence and a large increase in recognition for the last stimulus in each sequence. The recency effect was not altered by an intervening 30-sec delay, an intervening 30-sec copying task, or an intervening 30-sec copying and counting task. Since neither visual nor verbal distractors altered recognition accuracy, it was suggested that all shapes were processed directly into long-term memory storage. It also was hypothesized that long-term storage of a nonverbal stimulus requires identification of a distinctive feature of the stimulus and that this process may continue for a brief period after actual stimulus offset.     

The psychophysical dimensions of similarity among random shapes

Six psychological dimensions were recovered from similarity judgments of 20 random forms using Kruskal’s nonmetric scaling technique. These were related to 10 physical factors describing the forms by using canonical correlation analysis and rotations of the resulting vectors. Four factors accounted for 2/3 of the variance of the intersection of the physical and psychological spaces for each of 11 Ss. The factors are described as Complexity, Curvature, Curvature Dispersion, and Straight-length Dispers ion. The problem of the proper psychological distance metric is discussed, and individual differences among Ss are analyzed. The results lead to the conclusion that the four major factors found may be good representations of processes occurring in the perceptual system.     

Preference, familiarity, and recognition after repeated brief exposures to random geometric shapes

Repeated one-millisecond exposures to random polygon targets have been shown to result in preference for the target shapes over similar distractor shapes in the absence of recognition (Knust-Wilson & Zajonc, 1980). Seamon, Brody, and Kauff (1983a) interpreted this preference-without-recognition effect in terms of a two-process model of recognition memory. The present set of experiments tested three predictions of the two-process model: Target discrimination equal to that found in the preference task should also occur when subjects make familiarity judgments; recognition performance should improve if the target stimuli are presented and tested with an easily encodable visual context; and both preference and familiarity judgments should be unaffected by manipulations of context. The results supported all three predictions. The implications of the results for a competing model proposed by Zajonc (1980) are also discussed.     

Mental rotation of random two-dimensional shapes

Two experiments are reported in which Ss were required to determine whether a random, angular form, presented at any of a number of picture-plane orientations, was a “standard” or “reflected” version. Average time required to make this determination increased linearly with the angular departure of the form from a previously learned orientation. The slope and intercept of the reaction-time (RT) function were virtually constant, regardless of the perceptual complexity of the test form and the orientation selected for initial learning.When Ss were informed in advance as to the identity and the orientation of the upcoming test form and, further, were permitted to indicate when they were prepared for its external presentation, RT for determining the version of the form was constant for all test-form orientations. However, the time needed to prepare for the test-form presentation increased linearly with the angular departure of the form from the learned orientation.It is argued that the processes both of preparing for and of responding to a disoriented test form consist of the mental rotation of an image, and that both sorts of mental rotation (pre-stimulus and post-stimulus) are carried out at essentially the same constant rate.     

The role of letter recognition in word recognition

In a paradigm that avoids methodological problems of earlier studies, evidence was gathered addressed to the question of whether we read letter by letter. If word recognition involves letter recognition, then the difficulty of recognizing a word should vary with the difficulty of recognizing its letters. This was tested by assessing letter difficulty in two letter discrimination tasks and in a letter naming task, and then comparing 15 adult subjects' visual recognition latency to 72 easy-letter words and to 72 difficult-letter words. Word frequency and word length were also manipulated. Results indicated no effect for letter difficulty, although recognition latency reliably decreased with word frequency and monotonically increased with word length (21 msec/letter), suggesting that we do not read letter by letter, but that whatever plays a role in word recognition is smaller than the word and correlated with word length in letters.     

Orthography shapes the perception of speech: The consistency effect in auditory word recognition

Inconsistency in the spelling-to-sound mapping hurts visual word perception and reading aloud (i.e., the traditional consistency effect). In the present experiment, we found a consistency effect in auditory word perception: Words with phonological rimes that could be spelled in multiple ways produced longer auditory lexical decision latencies and more errors than did words with rimes that could be spelled only one way. This finding adds strong support to the claim that orthography affects the perception of spoken words. This effect was predicted by a model that assumes a coupling between orthography and phonology that is functional in both visual and auditory word perception.     

The role of familiarity in recognition

The role of familiarity in recognition was investigated by having subjects study a list of stimuli, some of which had been presented earlier in the experiment. The number of positive responses, both to targets and distractors, increased as a result of this familiarization process. This familiarization process had a greater effect on false alarms than on hits, so that recognition accuracy was lower for familiar stimuli than for relatively novel stimuli. This pattern of results differs from that found in most experiments studying the effects of linguistic word frequency on recognition.     

The role of generation in recognition

In contrast to the widely accepted opinion, a negatively accelerated RT function was obtained with varied mapping of stimuli to responses in Sternberg's (1966) recognition task when the task was designed to reduce proactive inhibition. These results are similar to the results obtained in the distractor task. Those aspects of the distractor task that proactively inhibit recall of the trigram are also necessary to produce a linear RT function in the recognition task. Hence, the varied-set procedure only results in a linear RT function when the memory sets on successive trials contain similar items, but not when successive trials contain different kinds of items, e.g., digits versus letters. Also, once subjects have been trained on the fixed-set procedure to produce a negatively accelerated RT function, the training transfers completely and immediately to entirely new sets of targets and distractors. The results of both tasks, as well as other retrieval tasks, can be explained by a model containing a single comparison process and an optional serial generation process which is invoked to increase the discriminability of the memory set from distractors.     

How evolutionary history shapes recognition mechanisms

Evolutionary psychologists have emphasized the importance of natural selection in shaping cognitive functions, but historical contingency has not received direct study. This is crucial because in response to selection, complex traits tend to be fine-tuned or jury-rigged rather than totally reconstructed. We hypothesize that the neural and cognitive strategies an animal employs in signal recognition are influenced by the strategies used by its ancestors. The responses of female túngara frogs to ancestral calls and to calls of other closely related species are influenced by history. By training artificial neural networks with a series of calls that mimic the species' past history of call evolution or various control histories, we have shown that only networks that evolved through the mimetic history predict the response biases of túngara frogs.     

The role of symmetry in determining perceived centers within shapes

This study was designed to assess the effects of symmetry and plane of presentation on the determination of the perceptual center of flat figures. Experiment 1 demonstrates the existence of effects in improving center determination, both in the number of sides of the shape and in rotational and reflective symmetry (confounded in the experiment). Experiment 2 shows that the presentation plane has no effect on center determination. In Experiment 3, we divide the effects of the two symmetry types, showing that rotational symmetry alone is as effective as the presence of both symmetry types—that is, the presence of symmetry axes is not very useful in finding perceived centers.     

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.     

The role of eyebrows in face recognition

A fundamental challenge in face recognition lies in determining which facial characteristics are important in the identification of faces. Several studies have indicated the significance of certain facial features in this regard, particularly internal ones such as the eyes and mouth. Surprisingly, however, one rather prominent facial feature has received little attention in this domain: the eyebrows. Past work has examined the role of eyebrows in emotional expression and nonverbal communication, as well as in facial aesthetics and sexual dimorphism. However, it has not been made clear whether the eyebrows play an important role in the identification of faces. Here, we report experimental results which suggest that for face recognition the eyebrows may be at least as influential as the eyes. Specifically, we find that the absence of eyebrows in familiar faces leads to a very large and significant disruption in recognition performance. In fact, a significantly greater decrement in face recognition is observed in the absence of eyebrows than in the absence of eyes. These results may have important implications for our understanding of the mechanisms of face recognition in humans as well as for the development of artificial face-recognition systems.