Recognition (Psychology)

In the current experiment, a group of 10-year-olds and a group of young adults
watched a series of short video clips of different women performing different actions.
One week later, participants were tested on their ability to discriminate the old videos
from distracter videos, which included new actor/old action videos, new action/old actor
videos, novel combinations of familiar actors and actions, as well as entirely new videos.
The results provide evidence that the ability to accurately bind actors with their actions
reaches adult levels by age 10. The results are discussed in terms of the brain areas
involved in memory binding tasks, as well as implications for various areas of study
within forensic psychology, particularly unconscious transference.

Most of the human visual field falls in the periphery, and peripheral processing is
important for normal visual functioning. Yet, little is known about peripheral object
recognition in naturalistic scenes and factors that modulate this ability. We propose that
a critical function of scene and object memory is in order to facilitate visual object
recognition in the periphery. In the first experiment, participants identified objects in
scenes across different levels of familiarity and contextual information within the scene.
We found that familiarity with a scene resulted in a significant increase in the distance
that objects were recognized. Furthermore, we found that a semantically consistent scene
improved the distance that object recognition is possible, supporting the notion that
contextual facilitation is possible in the periphery. In the second experiment, the preview
duration of a scene was varied in order to examine how a scene representation is built and
how memory of that scene and the objects within it contributes to object recognition in
the periphery. We found that the closer participants fixated to the object in the preview,
the farther on average they recognized that target object in the periphery. However, only a preview duration of the scenes for 5000 ms produced significantly farther peripheral
object recognition compared to not previewing the scene. Overall, these experiments
introduce a novel research paradigm for object recognition in naturalistic scenes, and
demonstrates multiple factors that have systematic effects on peripheral object
recognition.

The endogenous, or voluntary, control of visuospatial attention relies upon
interactions within a frontoparietal dorsal attention network (DAN) and this network’s
top-down influence on visual occipital cortex (VOC). While these interactions have been
shown to occur during attention tasks, they are also known to occur to some extent at rest,
but the degree to which task-related interactions reflect either modulation or
reorganization of such ongoing intrinsic interactions is poorly understood. In addition, it
is known that in spatial neglect—a syndrome following unilateral brain lesions in which
patients fail to attend to the contralesional side of space—symptom severity covaries with
disruptions to intrinsic interhemispheric interactions between left and right homologous
regions of the DAN; however, similar covariance with disruptions to intrahemispheric
interactions within the DAN, and between the DAN and VOC, has not been demonstrated.
These issues are addressed herein via the measurement of both undirected and directed
functional connectivity (UFC, DFC) within the DAN and between the DAN and VOC. UFC and DFC were derived from correlations of, and multivariate vector autoregressive
modeling of, fMRI BOLD time-series, respectively. Time-series were recorded from
individuals performing an anticipatory visuospatial attention task and individuals at rest,
as well as from stroke patients either with or without neglect and age-matched healthy
controls. With regard to the first issue, the results show that relative to rest, top-down
DAN-to-VOC influence and within-DAN coupling are elevated during task performance,
but also that intrinsic connectivity patterns are largely preserved during the task. With
regard to the second issue, results show that interhemispheric imbalances of
intrahemispheric UFC and DFC both within the DAN and between the DAN and VOC
strongly correlate with neglect severity, and may co-occur with functional decoupling of
the hemispheres. This work thus demonstrates that the intrinsic functional integrity of the
DAN and its relationship to VOC is crucial for the endogenous control of visuospatial
attention during tasks, and that the compromise of this integrity due to stroke likely plays
a role in producing spatial neglect.

The effects of retinal and objective orientation on recognition of novel
stimuli were examined in a two-phase experiment. In Phase 1 novel stimuli
were presented to tilted subjects placed in either an intentional
learning condition (they were instructed to remember the stimuli) or an
incidental learning condition (they received no instruction regarding
memory). In Phase 2 the same stimuli were randomly mixed with distractor
stimuli in a recognition test. Stimuli were presented to upright
subjects in either their objectively upright orientation (the same
orientation relative to gravity as in Phase 1) or their retinally upright
orientation (the same orientation relative to subjects' tilted
retinas as in Phase 1). The instructions produced no effect on recognition.
Evidence that both retinal and objective orientation influenced
recognition was obtained in both conditions. Alternative interpretations
hypothesized that: (1) dual memory representations of Phase 1
stimuli, referenced to both retinal and objective upright, were formed
and (2) a single memory representation of Phase 1 stimuli, referenced to
an axis intermediate to retinal and objective upright, was formed.

Individual differences were obtained in a task requiring
the reproduction of familiar and unfamiliar dot patterns.
These individual differences were related to Hock's (1973)
distinction between Ss emphasizing analytic vs. structural
processes. For some Ss (structural), reproductive performance
was facilitated by past experience, presumably because
these Ss acquired a structural organizational scheme of
knowledge. For the other Ss (analytic), reproductive performance
was retarded by past experience, presumably because
these Ss acquired a knowledge of "distinctive" features.

Rock's procedure for separating the effect of objective
and retinal spatial reference by varying stimulus orientation
and body posture was used in conjunction with the "same-different"
reaction time paradigm. It was predicted that
the individual differences in perceptual processing (analytic
and structural) obtained by Hock (1973) would involve
different determinants of spatial reference, these being
retinal reference for analytic processing and objective
reference for structural processing. The results show that
analytic subjects as hypothesized, referenced perceptual
information to a retinal coordinate system. Structural
subjects however, seemed to reference perceptual information
to both objective and retinal coordinates. The results for
structural subjects were attributed to the unexpected finding
that subjects who were structural while upright, became
analytic when in a reclining position. The latter finding
suggested that Rock's methodology for separating the effects
of retinal and objective orientation relies on the subjects
employing the same mode of processing in all bodily postures.

A probe recognition task tested memory for syntactic (active/passive arid
word order) changes and for semantic (meaningful and anomalous) changes.
On the basis of McNeill's theory of semantic development the following
predictions were made: (a) with a minimal retention interval (almost
immediate) 8-year-olds would recognize semantic changes better than
syntactic changes, while 6-year-olds would not perform differently on
the two types of changes, (b) with a longer retention interval, 8-year-olds
would recognize semantic changes better than syntactic changes. Results
supported (b) but in (a) the 8-year-olds recognized syntactic changes
better. This finding was discussed in terms of task differences and a new
experimental approach was proposed.

A stimulus class was generated by applying a fixed set of
transformational rules to a prototype, and selected members
of this class were presented during acquisition. It was found
that children discriminated members of this class from nonmembers.
For adults, further distinctions were obtained among
the stimuli within the class, as follows: Although the prototype
was not presented during acquisition, it was recognized
with greater confidence than stimuli from the acquisition set. Furthermore, class members that were not seen during acquisition
were recognized on the basis of this prototype. For those
class members that had been seen during acquisition, however,
there was no evidence that their recognition was based on the
prototype. Evidence that these previously seen class members
were recognized with greater confidence than new class members
indicated that recognition of stimuli from the acquisition
set was based on stored copies, or specific memory.

Visual average evoked potentials (AEPs) were recorded
from four male Ss in a sequential, single digit problem
solving task requiring addition of the first digit to the
second. Separate AEPs for the first and second digits
allowed Late Positive Component comparisons. It was
hypothesized that LPC latency variations are a function of
cognitive evaluation of information, with the prediction
that there would be a normal latency LPC in the first digit
AEP, where S recognizes a stimulus, as compared to a
delayed LPC in the second digit AEP where S must both
recognize and cognitively evaluate information to solve
the addition problem. Two experimental conditions, varying
stimulus presentation time between long and short, were run.
Equipment failure terminated the experiment and the
proposed study could not be researched. The pilot data
gathered were too variable and incomplete to permit conclusions.
However, these data did not contradict the hypothesis.

Experimental and computational investigations addressing how various neural functions are achieved in the brain converged in recent years to a unified idea that the neural activity underlying most of the cognitive functions is distributed over large scale networks comprising various cortical and subcortical areas. Modeling approaches represent these areas and their connections using diverse models of neurocomputational units engaged in graph-like or neural field-like structures. Regardless of the manner of network implementation, simulations of large scale networks have encountered significant difficulties mainly due to the time delay introduced by the long range connections. To decrease the computational effort, it is common to assume severe approximations to simplify the descriptions of the neural dynamics associated with the system's units. In this dissertation we propose an alternative framework allowing the prevention of such strong assumptions while efficiently representing th e dynamics of a complex neural network. First, we consider the dynamics of small scale networks of globally coupled non-identical excitatory and inhibitory neurons, which could realistically instantiate a neurocomputational unit. We identify the most significant dynamical features the neural population exhibits in different parametric configuration, including multi-cluster dynamics, multi-scale synchronization and oscillator death. Then, using mode decomposition techniques, we construct analytically low dimensional representations of the network dynamics and show that these reduced systems capture the dynamical features of the entire neural population. The cases of linear and synaptic coupling are discussed in detail. In chapter 5, we extend this approach for spatially extended neural networks.