Fig 1.
Examples of bipartite stimuli.
A portion of a well-known object was sketched on one side of the central border of stimuli in which two equal-area regions, one black and one white lay on opposite sides of that border. One, “critical”, region depicted a well-known object in an upright or an inverted orientation and was equally often on the left and right, in black and white. A. The critical region depicting a portion of a woman in an upright orientation is on the left in black. B. An inverted version of A. C. The critical region depicts a portion of a bell in an upright orientation in black on the right side. D. An inverted version of C. Black/white color of the critical regions was balanced in the experiments.
Fig 2.
Skocypec and Peterson’s behavioral results [19].
(First column) study 1; (Second column) study 2. (First row) Accuracy; (Second row) response times. Blue bars: Performance with upright displays; Red bars: Performance with inverted displays. White asterisks indicate main effects of labels-present vs. labels-absent control groups. Horizontal lines and black asterisks indicate orientation-dependent differences. Error bars represent pooled standard errors. *** indicates p < 0.001, * indicates p < 0.05.
Fig 3.
Different cases of drift diffusion model.
(A) A basic drift diffusion model over time. The x-axis represents time in seconds, and the y-axis represents evidence accumulation, which could be a cognitive or a perceptual process leading towards a decision. The dashed lines at the top and bottom represent decision thresholds for two choices, labeled as “Right” and “Left”, denoting by and
separately. Evidence accumulates over time, starting from
and fluctuating until it reaches one of the thresholds, indicating a decision has been made. The double headed arrow denotes the non-decision time,
. In A, the evidence crosses the upper threshold, suggesting a decision made towards the “Right side” option. (B) A decision process with a positive drift rate, v, on evidence accumulation (v > 0). A positive drift rate indicates a tendency for the evidence to accumulate towards the “Right side” choice over time. (C) A negative drift rate (v < 0) indicates a tendency to accumulate evidence towards the “Left side” choice. (D) A lower signal-to-noise ratio where there is more variability and noise in the evidence accumulation process than in C, resulting in a longer path to a decision threshold. (E) A higher threshold condition where more evidence must be accumulated before decision. (F) Evidence accumulation begins with a bias towards the “Right” choice, starting above zero, indicating a predisposition towards that option. (G) The opposite initial bias towards the “Left” choice, with evidence accumulation starting below zero.
Fig 4.
Trial structures for labels-present and labels-absent studies.
(A) Trial structure for labels absent experiments (control studies). Each trial began with a fixation point shown on a medium gray background (which was used throughout), followed by a 100 ms blank screen. Then, the stimulus was presented for 90 ms or 100 ms to different groups, followed by a mask for 200 ms and then by a blank screen. (B) Trial structures for labels present experiments, the critical difference from control is that, after the fixation cross, a word label appeared in the center of the screen for 250 ms. The label was either valid, denoting the object in the upcoming bipartite display at a basic level, or invalid, denoting a different unrelated object. Invalid labels in study 1 denoted an object in a different superordinate-level category (i.e., natural vs. artificial), denoted by “DSC” in the figure; invalid labels in study 2 denoted an object in the same superordinate-level category, denoted by “SSC” in the figure. The inset shows sample invalid labels for the object depicted in the bipartite display (i.e., bell) in study 1 (S1) and study 2 (S2). For a complete listing of the invalid labels see the Appendix in Skocypec and Peterson [19].
Fig 5.
Accuracy (column 1) and response times (RTs) in seconds (column 2) for both experimental data and data simulated from the model for both control (row 1) and experimental studies 1 and 2 (rows 2 & 3, respectively).
Blue bars represent the upright condition(“Up”). Red bars represent the inverted condition (“Inv”). Filled bars represent Skocypec & Peterson’s [19] behavioral data; striped bars represent data generated from the analytical expression of the model “Mo”). Error bars represent pooled standard errors. *** indicates p < 0.001.
Table 1.
Increments of drift rates in studies 1 and 2 over control.
Fig 6.
Model parameters in labels-present studies.
(First row) drift rate (v). (Second row left) threshold (a). (Second row right) starting point (z). Note the different scales on the ordinates of the figures in the second row. (Third row) non-decision time (.). Higher values indicate a greater drift rate/threshold/starting point/non-decision time. For starting point, positive values indicate starting points toward the right side, negative values indicate starting points toward the left side. (Left column) study 1; (Right Column) study 2. White asterisks indicate statistically significant increments over control. Error bars represent pooled standard errors. *** = p < 0.001, ** = p < 0.01, and * = p < 0.05.
Fig 7.
Potential mechanisms operative in Skocypec and Peterson’s object detection task [19].
Solid black lines with double-headed arrow endings indicate reentrant activity initiated by the object in the bipartite test display, both within the semantic network and between the semantic network and a lower-level representation of the test display (shown below the semantic network). Dashed lines with double-headed arrow endings indicate reentrant activation in the semantic network initiated by labels shown before the test displays, blue for valid labels, red or purple for invalid labels. Blue circles in the semantic network indicate semantic representations of the object in the test display in the various portions of the semantic network (e.g., context, object, etc.). Red & purple circles indicate semantic representations of objects denoted by invalid labels. Object NP = neural population representing an object. A) control labels-absent study. B) Valid labels in labels-present studies. (C-D) Invalid labels in labels-present studies; C) different superordinate-level invalid label as in study 1. D) same superordinate-level invalid label as in study 2. The green arrow labeled “R” emerging from the object NP in the semantic network indicates the participant’s right or left response; it’s shown in black to indicate that although the drift rate and threshold are affected by activity throughout the semantic network which affects activity within the NP representing the object, the R/L response must be dominated by recurrent activity between that NP and a lower-level representation of the object in the display.