Matched Outcomes, Divergent Gaze: How Foveated MLLMs Search Compared to Humans

Mohamed Amine Kerkouri; Marouane Tliba; Aladine Chetouani; Ulas Bagci; Alessandro Bruno

Figure 1: The dissociation on individual trials. Rows are (scene, target) target-present trials ordered by human search difficulty; columns are one human observer and Qwen3.5-35B-A3B (seed

0

) under four conditions. Green box, target; square, first fixation; numbered circles, fixation order; filled final marker, target found. Where the human accumulates fixations across the scene before confirming the target, the model under sharp and geisler–perry , visually indistinguishable conditions, issues one large saccade to the target and stops: the same outcome reached by a different process, and the divergence is in the order and extent of fixations rather than in their location. Row 6 is a human miss the model does not make. Under gist-

k{=}32

and crop the model does not search longer but terminates in false absence. Rows are illustrative, selected as trials spanning the range of human search difficulty; quantitative claims on the finding axis rest on all 141 target-present trials.

Figure 2: The three-axis dissociation at the human-matched condition. Decision (

d^{\prime}

, present/absent): the models match or exceed the human reference. Finding (first-saccade TFP@1): the models exceed the human rate (0.49) by a wide margin. Gaze (cross-seed self-consistency): all three lie above the human

\leftrightarrow

human ceiling (0.53) and apart from the human (bar height, cross-seed ScanMatch; annotation, gaze-entropy Cliff’s

\delta

), with Gemma-4-E4B nearest. The correct outcome is produced by a shared, non-human process.

Figure 3: The search loop. Each episode begins at a forced central fixation; the renderer applies the active foveation condition at the current gaze point, the resulting glimpse is appended to the context, and the model returns a single directive line. A look directive supplies normalised coordinates that are mapped to display pixels and become the next gaze point, closing the loop (red); found or absent terminates the episode (green). No search policy is imposed and the glimpse cap never forces termination: every episode ends on the model’s own decision.

Figure 4: The foveation bracket applied to one scene at a fixed gaze point (red

+

). Only geisler–perry is human-matched, and at this geometry it is mild, nearly indistinguishable from sharp ; the gaussian gist ladder and crop are synthetic anchors.

condition	Q	G	Gm	Q	G	Gm	Q	G	Gm	Q	G	Gm	Q	G	Gm	Q	G	Gm
	TFP@1			TFP-end			NFix-TP			NFix-TA			TA decl.-abs			dens. CC
human	0.49			0.93			3			5			—			—
sharp	0.97	0.97	0.80	0.97	0.98	0.93	2	2	3	1	4	6	0.94	0.91	0.96	0.55	0.54	0.49
GP	0.97	0.97	0.80	0.98	0.98	0.93	2	2	3	1	4	5	0.93	0.91	0.96	0.58	0.63	0.50
k8	0.93	0.84	0.64	0.95	0.89	0.86	3	2	3	2	4	6	0.84	0.77	0.81	0.65	0.45	0.26
k16	0.78	0.71	0.42	0.91	0.80	0.75	3	3	4	4	4	6	0.78	0.77	0.68	0.70	0.38	0.45

Table 1: Outcome by foveation condition (existence-passed trials); each entry is Qwen/GLM/Gemma (Q/G/Gm) against the human reference (first row; per-model

n

differs slightly). Finding and outcome measures match or exceed the human values; the dynamic gaze divergence is quantified in Table 2 , though target-absent search length (NFix-TA) also differs from humans for Qwen. TFP@

1

/TFP-end: target fixated on the first / by the final saccade (TP); NFix-TP/-TA: median fixations on target-present/absent trials; TA decl.-abs: target-absent declared-absent rate; dens. CC: correlation of model and human fixation-density maps.

cond.	model	entropy $\delta$	sacc. amp $\delta$	refix. $\delta$	center bias $\delta$	agent $\leftrightarrow$ agent
human $\leftrightarrow$ human ceiling		—	—	—	—	0.53
GP	Qwen3.5-35B-A3B	$-$ .67	$+$ .50	$+$ .04	$-$ .18	0.84
	GLM-4.6V-Flash	$-$ .65	$+$ .61	$-$ .13	$-$ .31	0.91
	Gemma-4-E4B	$-$ .27	$+$ .23	$+$ .13	$+$ .06	0.71
k16	Qwen3.5-35B-A3B	$-$ .56	$-$ .03	$+$ .49	$+$ .01	0.78
	GLM-4.6V-Flash	$-$ .53	$+$ .20	$+$ .30	$-$ .05	0.80

Table 2: Gaze axis at the human-matched condition and at two intermediate degradations, re-analysed from the per-condition tables of the submission (Tables S3–S4). Cliff’s

\delta

against the human distribution (

|\delta|>0.33

in bold; sign is agent

-

human) and cross-seed self-consistency. At GP the deviation is shared: low entropy, large amplitudes, near-human center bias. At k16–k24 the amplitude effect vanishes, refixation rises, and Gemma-4-E4B’s entropy reverses sign, so the GP signature is a property of the legible regime rather than a fixed offset; self-consistency above the ceiling is what persists for the two reasoning-tuned models.

Figure 5: ( 5(a) ) First-saccade targeting (solid) and eventual success (dashed) as functions of the degradation factor

k

for the three models, with human reference levels; the two quantities fall together, so no

k

yields human-like search at human-like success. ( 5(b) ) Principal-component analysis of the per-(model, condition) five-statistic gaze signature (PC1, 45%: scanpath length and gaze entropy; PC2, 30%: saccade amplitude versus refixation). Under the legible conditions each model sits in a region offset from the human reference (

\star

); points approach the human only under severe degradation, with Gemma-4-E4B nearest.

model	TP exist.	TA exist.	yes-bias	$d^{\prime}$ (GP)	criterion
human	—	—	—	2.91	0.03
Qwen3.5-35B-A3B	0.99	0.81	0.19	3.84	-0.41
GLM-4.6V-Flash	0.99	0.81	0.19	4.23	-0.24
Gemma-4-E4B	0.97	0.80	0.20	3.14	0.38

Table S1 : Detection and decision measures. One-shot existence accuracy and yes-bias (full sharp scene), the in-harness present/absent sensitivity

d^{\prime}

and criterion

c

at the human-matched condition (Eq. ( S2 )).

Figure S1 : Signal-detection sensitivity (

d^{\prime}

) and criterion (

c

) for the in-harness present/absent decision, per model against the human reference.

condition	Q	G	Gm	Q	G	Gm	Q	G	Gm	Q	G	Gm	Q	G	Gm	Q	G	Gm
	TFP@1			TFP-end			NFix-TP			NFix-TA			TA decl.-abs			dens. CC
human	0.49			0.93			3			5			—			—
sharp	0.97	0.97	0.80	0.97	0.98	0.93	2	2	3	1	4	6	0.94	0.91	0.96	0.55	0.54	0.49
GP	0.97	0.97	0.80	0.98	0.98	0.93	2	2	3	1	4	5	0.93	0.91	0.96	0.58	0.63	0.50
k8	0.93	0.84	0.64	0.95	0.89	0.86	3	2	3	2	4	6	0.84	0.77	0.81	0.65	0.45	0.26
k16	0.78	0.71	0.42	0.91	0.80	0.75	3	3	4	4	4	6	0.78	0.77	0.68	0.70	0.38	0.45

Table S2 : Outcome by foveation condition; each entry is Qwen / GLM / Gemma against the human reference (first row). TFP@1 and TFP-end follow Eq. ( S3 ); NumFix entries are per-group medians; the last two columns give target-absent declared-absent rate and fixation-density CC with the human map.

Figure S2 : Cumulative target-fixation probability by saccade (Eq. ( S3 )) under sharp (solid) and the human-matched GP (dotted) for the three models, against humans (dashed). The models reach the target on the first saccade; human probability accrues over several fixations.

model	condition	gaze entropy	saccade amp	refixation	scanpath len	center bias	turn angle	coverage
Q	sharp	$-$ .68	$+$ .52	$+$ .03	$-$ .27	$-$ .20	$+$ .03	$-$ .75
	GP	$-$ .67	$+$ .50	$+$ .04	$-$ .26	$-$ .18	$+$ .05	$-$ .74
	k8	$-$ .69	$+$ .20	$+$ .36	$-$ .27	$-$ .05	$+$ .06	$-$ .65
	k16	$-$ .56	$-$ .03	$+$ .49	$-$ .21	$+$ .01	$+$ .12	$-$ .46
	k24	$-$ .33	$-$ .08	$+$ .52	$-$ .07	$+$ .02	$+$ .14	$-$ .18
	k32	$-$ .15	$-$ .07	$+$ .50	$+$ .05	$+$ .00	$+$ .24	$-$ .03

Table S3 : Intrinsic gaze signature: Cliff’s

\delta

against the human distribution (Eq. ( S5 );

|\delta|>0.33

in bold; sign is agent

-

human) for every statistic and condition, for all three models. Human medians: gaze entropy

1.58

bits, saccade amplitude

8.57\textdegree

, refixation

0.00

, scanpath length

19.4\textdegree

, center bias

10.0\textdegree

.

Figure S3 : Per-scanpath gaze-statistic distributions at the human-matched condition, human against the three models. The reasoning-tuned models concentrate gaze (low entropy) and make large saccades; Gemma-4-E4B lies closest to the human distribution on the entropy, amplitude and scanpath-length panels (Qwen3.5-35B-A3B is closest on refixation).

Figure S4 : Distribution of ( 4(a) ) saccade directions and ( 4(b) ) turning angles at the human-matched condition. The models’ directional and meander structure departs from the human reference, consistent with the entropy and amplitude effects.

	Qwen3.5-35B-A3B		GLM-4.6V-Flash		Gemma-4-E4B
condition	AH	AA	AH	AA	AH	AA
human ceiling	0.53
sharp	0.500	0.839	0.484	0.903	0.473	0.712
GP	0.505	0.843	0.485	0.913	0.469	0.713
k8	0.527	0.814	0.491	0.868	0.462	0.697
k16	0.521	0.776	0.476	0.800	0.405	0.594

Table S4 : Scanpath similarity (ScanMatch, Sec. S3.5 ) by condition: agent

\leftrightarrow

human (AH) and agent

\leftrightarrow

agent (AA, cross-seed determinism) for each model. The human

\leftrightarrow

human agreement ceiling is 0.53.

component	variance	dominant loadings
PC1	45%	$+0.62$ gaze entropy, $+0.62$ scanpath len, $+0.41$ center bias
PC2	30%	$+0.69$ saccade amp, $-0.63$ refixation, $-0.35$ center bias

Table S5 : Principal components of the standardised five-statistic gaze signature across all groups, with the loadings that render the axes interpretable.

Figure S5 : Each statistic under sharp (abscissa) versus the human-matched GP condition (ordinate), per model. Points lie on the identity line: the human-matched foveation changes behaviour negligibly.

	sharp			geisler–perry
model	CC	NSS	KL	CC	NSS	KL
Qwen3.5-35B-A3B	0.55	0.57	1.39	0.58	0.60	1.30
GLM-4.6V-Flash	0.54	0.54	1.19	0.63	0.63	0.74
Gemma-4-E4B	0.49	0.48	0.47	0.50	0.48	0.46

Table S6 : Fixation-density agreement with the human map (Sec. S3.6 ) under sharp and the human-matched condition: linear correlation CC, normalised scanpath saliency NSS, and Kullback–Leibler divergence KL. CC and NSS (higher is closer) are highest for GLM-4.6V-Flash; KL (lower is closer) is lowest for Gemma-4-E4B. All three models correlate positively with the human map.

Figure S6 : Spatial agreement with humans (fixation-density CC, abscissa) against temporal divergence (absolute gaze-entropy effect, ordinate). The models match where humans look while diverging in how the looking unfolds.

Figure S7 : First-saccade targeting (solid) and eventual success (dashed) as functions of the synthetic degradation factor

k

, for the three models, with human reference levels. The two curves fall together; no

k

yields human-like search at human-like success.

Figure S8 : As degradation increases, the refixation effect (solid) rises (the models revisit locations) and then the declared-absent rate (dashed) rebounds at the most severe degradation as the models default to an absent response.

stratum (n)	human TFP@1	sharp TFP@1 (Q / G / Gm)
near-small (44)	0.54	0.96 / 0.97 / 0.76
near-large (26)	0.65	0.97 / 0.98 / 0.85
far-small (26)	0.37	1.00 / 0.98 / 0.64
far-large (45)	0.39	0.96 / 0.96 / 0.89

Table S7 : First-saccade targeting by eccentricity

\times

target-size stratum (sharp), human against the three models.

Figure S9 : First-saccade targeting per difficulty stratum; the models exceed humans in every eccentricity

\times

size cell, including the hardest.

model	max $\|\Delta$ TFP@1 $\|$ over $\pm 0.5/1/1.5\textdegree$
Qwen3.5-35B-A3B	0.063
GLM-4.6V-Flash	0.076
Gemma-4-E4B	0.095

Table S8 : Maximum absolute change in TFP@1 across box tolerances of

0.5

,

1

and

1.5

degrees, per model.

model	metric	sharp $\Delta$ [95% CI]	GP $\Delta$ [95% CI]
Qwen3.5-35B-A3B	gaze entropy	$-0.62$ [ $-0.69,-0.56$ ]	$-0.61$ [ $-0.67,-0.54$ ]
	saccade amp.	$+4.57$ [ $+3.19,+5.95$ ]	$+4.53$ [ $+3.15,+5.91$ ]
	NumFix	$-1.53$ [ $-1.94,-1.13$ ]	$-1.49$ [ $-1.89,-1.08$ ]
	TFP@1	$+0.47$ [ $+0.40,+0.54$ ]	$+0.48$ [ $+0.41,+0.55$ ]
GLM-4.6V-Flash	gaze entropy	$-0.60$ [ $-0.67,-0.52$ ]	$-0.60$ [ $-0.67,-0.52$ ]
	saccade amp.	$+5.58$ [ $+4.84,+6.32$ ]	$+5.62$ [ $+4.88,+6.35$ ]

Table S9 : Linear mixed-effects fixed effects against the human reference (Eq. ( S6 );

\Delta

[95% CI]) under sharp and the human-matched condition, with crossed scene and rater random intercepts. Bold indicates a confidence interval that excludes zero.

Figure S10 : Cross-seed self-consistency as a function of sampling temperature (anchor model, Qwen, core conditions), against the human

\leftrightarrow

human ceiling 0.53.

Matched Outcomes, Divergent Gaze: How Foveated MLLMs Search Compared to Humans

Abstract

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