Repetition costs in word identification: evaluating a stimulus–response integration account

Stimulus repetition facilitates performance in many experimental contexts. However, an episodic approach to interpreting repetition effects suggests that repetition effects should depend on how stimuli are encoded. In Experiments 1-3, stimulus repetition in a word identification task led to a cost rather than a benefit in performance, but only when the prime was presented for a relatively long duration. One account of these results is that long prime durations allow integration between stimulus and response codes to occur, which in turn can interfere with responding to a following identical target. In Experiment 4, a stimulus intensity based episodic specificity effect that was insensitive to the proportion of repeated trials supported this stimulus-response integration account.     

Big brown dog or brown big dog? An electrophysiological study of semantic constraints on prenominal adjective order

Event-related brain potentials (ERPs) were recorded while participants read and made acceptability judgments about sentences containing three types of adjective sequences: (1) normal sequences--e.g., Jennifer rode a huge gray elephant; (2) reversed sequences that violate grammatical-semantic constraints on linear order--e.g., *Jennifer rode a gray huge elephant; and (3) contradictory sequences that violate lexical-semantic constraints on compositionality--e.g., *Jennifer rode a small huge elephant. Relative to the control condition, the second adjective elicited a reduced N400 and an enhanced P600 in both the reversal condition and the contradiction condition. We present several alternative accounts of these two effects, but favor an interpretation which treats them as reflecting semantic and syntactic aspects of a temporary reanalysis of the adjective order construction. Furthermore, relative to the control condition, the final noun elicited a robust N400 in the contradiction condition but not in the reversal condition. We suggest that this effect indexes the full registration of the lexical-semantic incompatibility of the two adjectives in the contradiction condition. Finally, we discuss how all of these findings fit into the broader context of recent ERP studies that have reported atypical N400s and robust P600s in response to certain types of semantic anomalies.     

Is the psychological refractory period effect for ideomotor compatible tasks eliminated by speed-stress instructions?

It has been argued that the psychological refractory period (PRP) effect is eliminated with two ideomotor compatible tasks when instructions stress fast and simultaneous responding. Three experiments were conducted to test this hypothesis. In all experiments, Task 1 required spatially compatible manual responses (left or right) to the direction of an arrow, and Task 2 required saying the name of the auditory letter A or B. In Experiments 1 and 3, the manual responses were keypresses made with the left and right hands, whereas in Experiment 2 they were left-right toggle-switch movements made with the dominant hand. Instructions that stressed response speed reduced reaction time and increased error rate compared to standard instructions to respond fast and accurately, but did not eliminate the PRP effect on Task 2 reaction time. These results imply that, even when response speed is emphasized, ideomotor compatible tasks do not bypass response selection.     

Now you see me,now you don't: evidence that chimpanzees understand the role of the eyes in attention

Chimpanzees appear to understand something about the attentional states of others; in the present experiment, we investigated whether they understand that the attentional state of a human is based on eye gaze. In all, 116 adult chimpanzees were offered food by an experimenter who engaged in one of the four experimental manipulations: eyes closed, eyes open, hand over eyes, and hand over mouth. The communicative behavior of the chimpanzees was observed. More visible behaviors were produced when the experimenter's eyes were visible than when the experimenter's eyes were not visible. More vocalizations were produced when the experimenter's eyes were closed than when they were open, but there were no differences in other attention getting behaviors. There was no effect of age or rearing history. The results suggest that chimpanzees use the presence of the eyes as a cue that their visual gestures will be effective.     

Face processing in humans and new world monkeys: the influence of experiential and ecological factors

This study tests whether the face-processing system of humans and a nonhuman primate species share characteristics that would allow for early and quick processing of socially salient stimuli: a sensitivity toward conspecific faces, a sensitivity toward highly practiced face stimuli, and an ability to generalize changes in the face that do not suggest a new identity, such as a face differently oriented. The look rates by adult tamarins and humans toward conspecific and other primate faces were examined to determine if these characteristics are shared. A visual paired comparison (VPC) task presented subjects with either a human face, chimpanzee face, tamarin face, or an object as a sample, and then a pair containing the previous stimulus and a novel stimulus was presented. The stimuli were either presented all in an upright orientation, or all in an inverted orientation. The novel stimulus in the pair was either an orientation change of the same face/object or a new example of the same type of face/object, and the stimuli were shown either in an upright orientation or in an inverted orientation. Preference to novelty scores revealed that humans attended most to novel individual human faces, and this effect decreased significantly if the stimuli were inverted. Tamarins showed preferential looking toward novel orientations of previously seen tamarin faces in the upright orientation, but not in an inverted orientation. Similarly, their preference to look longer at novel tamarin and human faces within the pair was reduced significantly with inverted stimuli. The results confirmed prior findings in humans that novel human faces generate more attention in the upright than in the inverted orientation. The monkeys also attended more to faces of conspecifics, but showed an inversion effect to orientation change in tamarin faces and to identity changes in tamarin and human faces. The results indicate configural processing restricted to particular kinds of primate faces by a New World monkey species, with configural processing influenced by life experience (human faces and tamarin faces) and specialized to process orientation changes specific to conspecific faces.