Conclusion: The Blank Interval

How can we look more closely at movements in animated films? The preceding pages have offered one answer to this question. By looking for figures that are held together or apart by forces, this book has argued, we find a method for describing movements as coordinations of component parts....

Mismatch Negativity Does Not Show Evidence of Memory Reactivation in the Visual Modality

The possibility of reactivation of the memory representation underlying visual mismatch negativity (vMMN) was investigated in a modified passive roving-standard paradigm. Stimuli (arrays of Gábor patches) were presented in sequences with blank interval between the sequences. The first member of each sequence was identical to the standard of the previous sequence, while the second stimulus had different orientation therefore the second stimulus was considered as deviant. In a control condition the stimuli of the previous sequence had random orientations. Event-related potentials (ERPs) in response to the deviants were compared to ERPs in response to the (physically identical) second stimulus of the control sequences. The comparison showed emergence of a positive component at an early (98–132 ms) latency range elicited by deviants. This component is interpreted as an index of increased sensitivity to rare changes in sequences dominated by identical stimuli rather than a component specific to violation of sequential regularity. Consequently, contrary to the findings in the auditory modality, the first stimulus of the sequence did not reactivate the memory representation underlying the vMMN, since subsequent deviant elicited no vMMN.

What You Fear Will Appear

Various experimental tasks suggest that fear guides attention. However, because these tasks often lack ecological validity, it is unclear to what extent results from these tasks can be generalized to real-life situations. In change detection tasks, a brief interruption of the visual input (i.e., a blank interval or a scene cut) often results in undetected changes in the scene. This setup resembles real-life viewing behavior and is used here to increase ecological validity of the attentional task without compromising control over the stimuli presented. Spider-fearful and nonfearful women detected schematic spiders and flowers that were added to one of two identical background pictures that alternated with a brief blank in between them (i.e., flicker paradigm). Results showed that spider-fearful women detected spiders (but not flowers) faster than did nonfearful women. Because spiders and flowers had similar low-level features, these findings suggest that fear guides attention on the basis of object features rather than simple low-level features.

Long-term Expertise with Artificial Objects Increases Visual Competition with Early Face Categorization Processes

The degree of commonality between the perceptual mechanisms involved in processing faces and objects of expertise is intensely debated. To clarify this issue, we recorded occipito-temporal event-related potentials in response to faces when concurrently processing visual objects of expertise. In car experts fixating pictures of cars, we observed a large decrease of an evoked potential elicited by face stimuli between 130 and 200 msec, the N170. This sensory suppression was much lower when the car and face stimuli were separated by a 200-msec blank interval. With and without this delay, there was a strong correlation between the face-evoked N170 amplitude decrease and the subject's level of car expertise as measured in an independent behavioral task. Together, these results show that neural representations of faces and nonface objects in a domain of expertise compete for visual processes in the occipito-temporal cortex as early as 130–200 msec following stimulus onset.

Motor Encoding Strategy for Pitches of Melodies

The role of a motor strategy of pitch encoding in the processing of melodies was investigated. The encoding task involved finger-tapping analogous to that used in playing the piano. Twelve students highly trained in music made recognition judgments of melodies after a retention interval. Subjects were instructed to use tapping to memorize the pitches of the standard melody. The retention interval consisted of a blank interval, or was filled with an interfering melody, or a series of musical note names, in separate experiments. The findings suggest that (a) tapping can be an effective strategy for pitch encoding; (b) as melody length or duration of the retention interval increased, or when the retention interval was filled, subjects often tried to repeat the finger-tapping pattern in order to retain the standard melodies; (c) repeating the tapping pattern many times could elaborate the fingering of the tapping and consequently the encoding of the melodies; (d) some subjects used a dual encoding strategy, incorporating motor and verbal components.

Recognition of Non-Studied Visual Depictions of Aircraft: Improvement by Distributed Presentation

This experiment examined the effects of three methods of presentation, one massed and two distributed, on recognition of complex visual stimuli (military aircraft). Also examined was whether the effects of these methods differ as a function of the view at test (same or different from the studied view). In the massed presentation, aircraft were exposed once for eight seconds with each exposure separated by a blank interval of 20 seconds. In the successive distributed condition, each target aircraft was presented four times in a row for two seconds with each exposure separated by blank intervals of five seconds. In the random distributed condition, the aircraft were presented for the same on-off time intervals as the successive distributed condition, but the sequence of the study list was random. Results showed that recognition performance, as assessed by measures of hits, false alarms, and discrimination accuracy was significantly better when the same view was given at study and at test versus a different view. While presentation method did not produce an effect by itself, it did interact with test view. With a different view at test, distributed presentation showed a small, but significant, improvement in recognition performance compared to massed presentation. These results are discussed with regard to the high likelihood that most real-word visual stimuli are seen in a different views at subsequent exposures. Distributed presentation may be a useful way to prepare individuals for a different view at a later time.

III.—Some Recent Excavations in London

The discoveries recorded in the following pages cover, in more than one sense, a considerable period of time. Some of them were made as early as the spring of 1915, immediately after the present author had read a paper on a similar subject, which was later published in Archaeologia, lxvi. The bulk, however, are the fruits of the resumption of building operations in 1919 and 1920, after the great blank interval of the War. It is not proposed, in the description of the finds, to distinguish exactly between these periods, for the sites investigated fall by a happy chance into two groups–one in King William Street, the other about London Wall and Finsbury Circus–each of which can be treated as a whole. It will be sufficient for the present purpose to note that one site from each group–the Comptoir National from the first, and 12 to 26 Finsbury Circus from the second–was excavated in 1915, and the rest between the autumn of 1919 and the summer of 1921.